diff --git a/CHANGES.rst b/CHANGES.rst
index 9da7f855392..73ce2316c3b 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -6,7 +6,8 @@ CHANGES
 
 - Drop deprecated `WSClientDisconnectedError` (BACKWARD INCOMPATIBLE)
 
--
+- Use `yarl.URL` in client API. The change is 99% backward compatible
+  but `ClientResponse.url` is an `yarl.URL` instance now.
 
 -
 
diff --git a/README.rst b/README.rst
index 18f19abfdf3..808be0a58c8 100644
--- a/README.rst
+++ b/README.rst
@@ -116,8 +116,10 @@ Requirements
 ------------
 
 - Python >= 3.4.2
+- asyncio-timeout_
 - chardet_
 - multidict_
+- yarl_
 
 Optionally you may install the cChardet_ and aiodns_ libraries (highly
 recommended for sake of speed).
@@ -125,6 +127,8 @@ recommended for sake of speed).
 .. _chardet: https://pypi.python.org/pypi/chardet
 .. _aiodns: https://pypi.python.org/pypi/aiodns
 .. _multidict: https://pypi.python.org/pypi/multidict
+.. _yarl: https://pypi.python.org/pypi/yarl
+.. _asyncio-timeout: https://pypi.python.org/pypi/asyncio_timeout
 .. _cChardet: https://pypi.python.org/pypi/cchardet
 
 License
diff --git a/aiohttp/client.py b/aiohttp/client.py
index 4c616ef898d..c4b3f3a4d3b 100644
--- a/aiohttp/client.py
+++ b/aiohttp/client.py
@@ -6,10 +6,10 @@
 import os
 import sys
 import traceback
-import urllib.parse
 import warnings
 
 from multidict import CIMultiDict, MultiDict, MultiDictProxy, istr
+from yarl import URL
 
 import aiohttp
 
@@ -180,8 +180,11 @@ def _request(self, method, url, *,
             for i in skip_auto_headers:
                 skip_headers.add(istr(i))
 
+        if isinstance(proxy, str):
+            proxy = URL(proxy)
+
         while True:
-            url, _ = urllib.parse.urldefrag(url)
+            url = URL(url).with_fragment(None)
 
             cookies = self._cookie_jar.filter_cookies(url)
 
@@ -237,15 +240,15 @@ def _request(self, method, url, *,
                     if headers.get(hdrs.CONTENT_LENGTH):
                         headers.pop(hdrs.CONTENT_LENGTH)
 
-                r_url = (resp.headers.get(hdrs.LOCATION) or
-                         resp.headers.get(hdrs.URI))
+                r_url = URL(resp.headers.get(hdrs.LOCATION) or
+                            resp.headers.get(hdrs.URI))
 
-                scheme = urllib.parse.urlsplit(r_url)[0]
+                scheme = r_url.scheme
                 if scheme not in ('http', 'https', ''):
                     resp.close()
                     raise ValueError('Can redirect only to http or https')
                 elif not scheme:
-                    r_url = urllib.parse.urljoin(url, r_url)
+                    r_url = url.join(r_url)
 
                 url = r_url
                 params = None
diff --git a/aiohttp/client_reqrep.py b/aiohttp/client_reqrep.py
index 86310074f72..5ab83564647 100644
--- a/aiohttp/client_reqrep.py
+++ b/aiohttp/client_reqrep.py
@@ -1,5 +1,4 @@
 import asyncio
-import collections
 import http.cookies
 import io
 import json
@@ -7,10 +6,10 @@
 import os
 import sys
 import traceback
-import urllib.parse
 import warnings
 
 from multidict import CIMultiDict, CIMultiDictProxy, MultiDict, MultiDictProxy
+from yarl import URL
 
 import aiohttp
 
@@ -31,9 +30,6 @@
 
 PY_35 = sys.version_info >= (3, 5)
 
-HTTP_PORT = 80
-HTTPS_PORT = 443
-
 
 class ClientRequest:
 
@@ -75,7 +71,15 @@ def __init__(self, method, url, *,
         if loop is None:
             loop = asyncio.get_event_loop()
 
-        self.url = url
+        assert isinstance(url, URL), url
+        assert isinstance(proxy, (URL, type(None))), proxy
+
+        if params:
+            q = MultiDict(url.query)
+            url2 = url.with_query(params)
+            q.extend(url2.query)
+            url = url.with_query(q)
+        self.url = url.with_fragment(None)
         self.method = method.upper()
         self.encoding = encoding
         self.chunked = chunked
@@ -89,7 +93,6 @@ def __init__(self, method, url, *,
 
         self.update_version(version)
         self.update_host(url)
-        self.update_path(params)
         self.update_headers(headers)
         self.update_auto_headers(skip_auto_headers)
         self.update_cookies(cookies)
@@ -101,59 +104,30 @@ def __init__(self, method, url, *,
         self.update_transfer_encoding()
         self.update_expect_continue(expect100)
 
-    def update_host(self, url):
-        """Update destination host, port and connection type (ssl)."""
-        url_parsed = urllib.parse.urlsplit(url)
+    @property
+    def host(self):
+        return self.url.host
 
-        # check for network location part
-        netloc = url_parsed.netloc
-        if not netloc:
-            raise ValueError('Host could not be detected.')
+    @property
+    def port(self):
+        return self.url.port
 
+    def update_host(self, url):
+        """Update destination host, port and connection type (ssl)."""
         # get host/port
-        host = url_parsed.hostname
-        if not host:
+        if not url.host:
             raise ValueError('Host could not be detected.')
 
-        try:
-            port = url_parsed.port
-        except ValueError:
-            raise ValueError(
-                'Port number could not be converted.') from None
-
-        # check domain idna encoding
-        try:
-            host = host.encode('idna').decode('utf-8')
-            netloc = self.make_netloc(host, url_parsed.port)
-        except UnicodeError:
-            raise ValueError('URL has an invalid label.')
-
         # basic auth info
-        username, password = url_parsed.username, url_parsed.password
+        username, password = url.user, url.password
         if username:
             self.auth = helpers.BasicAuth(username, password or '')
 
         # Record entire netloc for usage in host header
-        self.netloc = netloc
 
-        scheme = url_parsed.scheme
+        scheme = url.scheme
         self.ssl = scheme in ('https', 'wss')
 
-        # set port number if it isn't already set
-        if not port:
-            if self.ssl:
-                port = HTTPS_PORT
-            else:
-                port = HTTP_PORT
-
-        self.host, self.port, self.scheme = host, port, scheme
-
-    def make_netloc(self, host, port):
-        ret = host
-        if port:
-            ret = ret + ':' + str(port)
-        return ret
-
     def update_version(self, version):
         """Convert request version to two elements tuple.
 
@@ -172,25 +146,8 @@ def update_version(self, version):
     def update_path(self, params):
         """Build path."""
         # extract path
-        scheme, netloc, path, query, fragment = urllib.parse.urlsplit(self.url)
-        if not path:
-            path = '/'
-
-        if isinstance(params, collections.Mapping):
-            params = list(params.items())
-
-        if params:
-            if not isinstance(params, str):
-                params = urllib.parse.urlencode(params)
-            if query:
-                query = '%s&%s' % (query, params)
-            else:
-                query = params
 
-        self.path = urllib.parse.urlunsplit(('', '', helpers.requote_uri(path),
-                                             query, ''))
-        self.url = urllib.parse.urlunsplit(
-            (scheme, netloc, self.path, '', fragment))
+        self.url = self.url.with_query(params)
 
     def update_headers(self, headers):
         """Update request headers."""
@@ -214,7 +171,10 @@ def update_auto_headers(self, skip_auto_headers):
 
         # add host
         if hdrs.HOST not in used_headers:
-            self.headers[hdrs.HOST] = self.netloc
+            netloc = self.url.host
+            if not self.url.is_default_port():
+                netloc += ':' + str(self.url.port)
+            self.headers[hdrs.HOST] = netloc
 
         if hdrs.USER_AGENT not in used_headers:
             self.headers[hdrs.USER_AGENT] = self.SERVER_SOFTWARE
@@ -378,7 +338,7 @@ def update_expect_continue(self, expect=False):
             self._continue = helpers.create_future(self.loop)
 
     def update_proxy(self, proxy, proxy_auth):
-        if proxy and not proxy.startswith('http://'):
+        if proxy and not proxy.scheme == 'http':
             raise ValueError("Only http proxies are supported")
         if proxy_auth and not isinstance(proxy_auth, helpers.BasicAuth):
             raise ValueError("proxy_auth must be None or BasicAuth() tuple")
@@ -488,7 +448,11 @@ def write_bytes(self, request, reader):
 
     def send(self, writer, reader):
         writer.set_tcp_cork(True)
-        request = aiohttp.Request(writer, self.method, self.path, self.version)
+        path = self.url.raw_path
+        if self.url.raw_query_string:
+            path += '?' + self.url.raw_query_string
+        request = aiohttp.Request(writer, self.method, path,
+                                  self.version)
 
         if self.compress:
             request.add_compression_filter(self.compress)
@@ -511,7 +475,7 @@ def send(self, writer, reader):
             self.write_bytes(request, reader), loop=self.loop)
 
         self.response = self.response_class(
-            self.method, self.url, self.host,
+            self.method, self.url, self.url.host,
             writer=self._writer, continue100=self._continue,
             timeout=self._timeout)
         self.response._post_init(self.loop)
@@ -556,7 +520,7 @@ class ClientResponse:
 
     def __init__(self, method, url, host='', *, writer=None, continue100=None,
                  timeout=5*60):
-        super().__init__()
+        assert isinstance(url, URL)
 
         self.method = method
         self.url = url
@@ -591,8 +555,7 @@ def __del__(self, _warnings=warnings):
 
     def __repr__(self):
         out = io.StringIO()
-        ascii_encodable_url = self.url.encode('ascii', 'backslashreplace') \
-            .decode('ascii')
+        ascii_encodable_url = str(self.url)
         if self.reason:
             ascii_encodable_reason = self.reason.encode('ascii',
                                                         'backslashreplace') \
diff --git a/aiohttp/connector.py b/aiohttp/connector.py
index 8ada87a55d6..cdfdca709bb 100644
--- a/aiohttp/connector.py
+++ b/aiohttp/connector.py
@@ -11,6 +11,8 @@
 from math import ceil
 from types import MappingProxyType
 
+from yarl import URL
+
 import aiohttp
 
 from . import hdrs, helpers
@@ -638,9 +640,7 @@ def _create_proxy_connection(self, req):
             raise ProxyConnectionError(*exc.args) from exc
 
         if not req.ssl:
-            req.path = '{scheme}://{host}{path}'.format(scheme=req.scheme,
-                                                        host=req.netloc,
-                                                        path=req.path)
+            req.path = str(req.url)
         if hdrs.AUTHORIZATION in proxy_req.headers:
             auth = proxy_req.headers[hdrs.AUTHORIZATION]
             del proxy_req.headers[hdrs.AUTHORIZATION]
@@ -723,6 +723,7 @@ def __init__(self, proxy, *, proxy_auth=None, force_close=True,
                          conn_timeout=conn_timeout,
                          keepalive_timeout=keepalive_timeout,
                          limit=limit, loop=loop)
+        assert isinstance(proxy, URL)
         self._proxy = proxy
         self._proxy_auth = proxy_auth
 
diff --git a/aiohttp/cookiejar.py b/aiohttp/cookiejar.py
index 907b0ca52fc..facd1e7b66c 100644
--- a/aiohttp/cookiejar.py
+++ b/aiohttp/cookiejar.py
@@ -4,7 +4,8 @@
 from collections.abc import Mapping
 from http.cookies import Morsel, SimpleCookie
 from math import ceil
-from urllib.parse import urlsplit
+
+from yarl import URL
 
 from .abc import AbstractCookieJar
 from .helpers import is_ip_address
@@ -76,10 +77,9 @@ def _expire_cookie(self, when, domain, name):
         self._next_expiration = min(self._next_expiration, when)
         self._expirations[(domain, name)] = when
 
-    def update_cookies(self, cookies, response_url=None):
+    def update_cookies(self, cookies, response_url=URL()):
         """Update cookies."""
-        url_parsed = urlsplit(response_url or "")
-        hostname = url_parsed.hostname
+        hostname = response_url.host
 
         if not self._unsafe and is_ip_address(hostname):
             # Don't accept cookies from IPs
@@ -119,7 +119,7 @@ def update_cookies(self, cookies, response_url=None):
             path = cookie["path"]
             if not path or not path.startswith("/"):
                 # Set the cookie's path to the response path
-                path = url_parsed.path
+                path = response_url.path
                 if not path.startswith("/"):
                     path = "/"
                 else:
@@ -152,13 +152,12 @@ def update_cookies(self, cookies, response_url=None):
 
         self._do_expiration()
 
-    def filter_cookies(self, request_url):
+    def filter_cookies(self, request_url=URL()):
         """Returns this jar's cookies filtered by their attributes."""
         self._do_expiration()
-        url_parsed = urlsplit(request_url)
         filtered = SimpleCookie()
-        hostname = url_parsed.hostname or ""
-        is_not_secure = url_parsed.scheme not in ("https", "wss")
+        hostname = request_url.host or ""
+        is_not_secure = request_url.scheme not in ("https", "wss")
 
         for cookie in self:
             name = cookie.key
@@ -178,7 +177,7 @@ def filter_cookies(self, request_url):
             elif not self._is_domain_match(domain, hostname):
                 continue
 
-            if not self._is_path_match(url_parsed.path, cookie["path"]):
+            if not self._is_path_match(request_url.path, cookie["path"]):
                 continue
 
             if is_not_secure and cookie["secure"]:
diff --git a/aiohttp/errors.py b/aiohttp/errors.py
index c7286a27568..85c6eed7ba9 100644
--- a/aiohttp/errors.py
+++ b/aiohttp/errors.py
@@ -176,7 +176,3 @@ def __repr__(self):
         return '<{} expected={} got={} host={} port={}>'.format(
             self.__class__.__name__, self.expected, self.got,
             self.host, self.port)
-
-
-class InvalidURL(Exception):
-    """Invalid URL."""
diff --git a/aiohttp/helpers.py b/aiohttp/helpers.py
index 5b3f524efe3..37329d58426 100644
--- a/aiohttp/helpers.py
+++ b/aiohttp/helpers.py
@@ -11,13 +11,12 @@
 import warnings
 from collections import namedtuple
 from pathlib import Path
-from urllib.parse import quote, urlencode
+from urllib.parse import urlencode
 
 from async_timeout import timeout
 from multidict import MultiDict, MultiDictProxy
 
 from . import hdrs
-from .errors import InvalidURL
 
 try:
     from asyncio import ensure_future
@@ -440,54 +439,6 @@ def __set__(self, inst, value):
         raise AttributeError("reified property is read-only")
 
 
-# The unreserved URI characters (RFC 3986)
-UNRESERVED_SET = frozenset(
-    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" +
-    "0123456789-._~")
-
-
-def unquote_unreserved(uri):
-    """Un-escape any percent-escape sequences in a URI that are unreserved
-    characters. This leaves all reserved, illegal and non-ASCII bytes encoded.
-    """
-    parts = uri.split('%')
-    for i in range(1, len(parts)):
-        h = parts[i][0:2]
-        if len(h) == 2 and h.isalnum():
-            try:
-                c = chr(int(h, 16))
-            except ValueError:
-                raise InvalidURL("Invalid percent-escape sequence: '%s'" % h)
-
-            if c in UNRESERVED_SET:
-                parts[i] = c + parts[i][2:]
-            else:
-                parts[i] = '%' + parts[i]
-        else:
-            parts[i] = '%' + parts[i]
-    return ''.join(parts)
-
-
-def requote_uri(uri):
-    """Re-quote the given URI.
-
-    This function passes the given URI through an unquote/quote cycle to
-    ensure that it is fully and consistently quoted.
-    """
-    safe_with_percent = "!#$%&'()*+,/:;=?@[]~"
-    safe_without_percent = "!#$&'()*+,/:;=?@[]~"
-    try:
-        # Unquote only the unreserved characters
-        # Then quote only illegal characters (do not quote reserved,
-        # unreserved, or '%')
-        return quote(unquote_unreserved(uri), safe=safe_with_percent)
-    except InvalidURL:
-        # We couldn't unquote the given URI, so let's try quoting it, but
-        # there may be unquoted '%'s in the URI. We need to make sure they're
-        # properly quoted so they do not cause issues elsewhere.
-        return quote(uri, safe=safe_without_percent)
-
-
 _ipv4_pattern = ('^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}'
                  '(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$')
 _ipv6_pattern = (
diff --git a/aiohttp/web.py b/aiohttp/web.py
index f06535c6aa2..434a5643586 100644
--- a/aiohttp/web.py
+++ b/aiohttp/web.py
@@ -16,7 +16,6 @@
 from .web_urldispatcher import *  # noqa
 from .web_ws import *  # noqa
 
-
 __all__ = (web_reqrep.__all__ +
            web_exceptions.__all__ +
            web_urldispatcher.__all__ +
diff --git a/docs/client_reference.rst b/docs/client_reference.rst
index 70ecea57184..ccb2a496251 100644
--- a/docs/client_reference.rst
+++ b/docs/client_reference.rst
@@ -1135,7 +1135,13 @@ Response object
 
    .. attribute:: url
 
-      URL of request (:class:`str`).
+      URL of request (:class:`~yarl.URL`).
+
+      .. versionchanged:: 1.1
+
+      The attribute is :class:`~yarl.URL` now instead of :class:`str`.
+
+      For giving a string use ``str(resp.url)``.
 
    .. attribute:: connection
 
diff --git a/docs/index.rst b/docs/index.rst
index 09e092aae52..01aefbfb525 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -122,10 +122,11 @@ Dependencies
 ------------
 
 - Python 3.4.2+
-- *chardet* library
-- *multidict* library
-- *async_timeout* library
-- *Optional* :term:`cchardet` library as faster replacement for
+- *chardet*
+- *multidict*
+- *async_timeout*
+- *yarl*
+- *Optional* :term:`cchardet` as faster replacement for
   :term:`chardet`.
 
   Install it explicitly via:
@@ -134,7 +135,7 @@ Dependencies
 
      $ pip install cchardet
 
-- *Optional* :term:`aiodns` library for fast DNS resolving. The
+- *Optional* :term:`aiodns` for fast DNS resolving. The
   library is highly recommended.
 
   .. code-block:: bash
diff --git a/requirements-ci.txt b/requirements-ci.txt
index aef1916adb4..9d6bdbfc61e 100644
--- a/requirements-ci.txt
+++ b/requirements-ci.txt
@@ -20,4 +20,5 @@ gunicorn
 pygments>=2.1
 #aiodns  # Enable from .travis.yml as required c-ares will not build on windows
 twine
+yarl
 -e .
diff --git a/setup.py b/setup.py
index 181ce680657..e703d49d72b 100644
--- a/setup.py
+++ b/setup.py
@@ -54,7 +54,7 @@ def build_extension(self, ext):
         raise RuntimeError('Unable to determine version.')
 
 
-install_requires = ['chardet', 'multidict>=2.0', 'async_timeout']
+install_requires = ['chardet', 'multidict>=2.0', 'async_timeout', 'yarl']
 
 if sys.version_info < (3, 4, 2):
     raise RuntimeError("aiohttp requires Python 3.4.2+")
diff --git a/tests/test_client_functional.py b/tests/test_client_functional.py
index 8c162122da5..5b0fa8aa577 100644
--- a/tests/test_client_functional.py
+++ b/tests/test_client_functional.py
@@ -391,7 +391,7 @@ def handler_ok(request):
     resp = yield from client.get('/redirect')
     try:
         assert resp.status == 200
-        assert resp.url.endswith('/ok')
+        assert resp.url.path == '/ok'
     finally:
         yield from resp.release()
 
@@ -408,7 +408,7 @@ def handler_ok(request):
     resp = yield from client.get('/ok#fragment')
     try:
         assert resp.status == 200
-        assert resp.url.endswith('/ok')
+        assert resp.url.path == '/ok'
     finally:
         yield from resp.release()
 
diff --git a/tests/test_client_request.py b/tests/test_client_request.py
index c68d3b0ba21..08daf1e2215 100644
--- a/tests/test_client_request.py
+++ b/tests/test_client_request.py
@@ -5,7 +5,6 @@
 import inspect
 import io
 import os.path
-import re
 import unittest
 import urllib.parse
 import zlib
@@ -14,6 +13,7 @@
 
 import pytest
 from multidict import CIMultiDict, CIMultiDictProxy, upstr
+from yarl import URL
 
 import aiohttp
 from aiohttp import BaseConnector, helpers
@@ -24,9 +24,9 @@
 def make_request(loop):
     request = None
 
-    def maker(*args, **kwargs):
+    def maker(method, url, *args, **kwargs):
         nonlocal request
-        request = ClientRequest(*args, loop=loop, **kwargs)
+        request = ClientRequest(method, URL(url), *args, loop=loop, **kwargs)
         return request
 
     yield maker
@@ -137,7 +137,7 @@ def test_host_header_host_without_port(make_request):
 
 def test_host_header_host_with_default_port(make_request):
     req = make_request('get', 'http://python.org:80/')
-    assert req.headers['HOST'] == 'python.org:80'
+    assert req.headers['HOST'] == 'python.org'
 
 
 def test_host_header_host_with_nondefault_port(make_request):
@@ -159,7 +159,7 @@ def test_host_header_explicit_host_with_port(make_request):
 
 def test_default_loop(loop):
     asyncio.set_event_loop(loop)
-    req = ClientRequest('get', 'http://python.org/')
+    req = ClientRequest('get', URL('http://python.org/'))
     assert req.loop is loop
 
 
@@ -219,7 +219,7 @@ def test_invalid_idna(make_request):
 
 def test_no_path(make_request):
     req = make_request('get', 'http://python.org')
-    assert '/' == req.path
+    assert '/' == req.url.path
 
 
 def test_ipv6_default_http_port(make_request):
@@ -275,7 +275,7 @@ def test_basic_auth_from_url(make_request):
     req = make_request('get', 'http://nkim:1234@python.org')
     assert 'AUTHORIZATION' in req.headers
     assert 'Basic bmtpbToxMjM0' == req.headers['AUTHORIZATION']
-    assert 'python.org' == req.netloc
+    assert 'python.org' == req.host
 
 
 def test_basic_auth_from_url_overriden(make_request):
@@ -283,49 +283,49 @@ def test_basic_auth_from_url_overriden(make_request):
                        auth=aiohttp.BasicAuth('nkim', '1234'))
     assert 'AUTHORIZATION' in req.headers
     assert 'Basic bmtpbToxMjM0' == req.headers['AUTHORIZATION']
-    assert 'python.org' == req.netloc
+    assert 'python.org' == req.host
 
 
 def test_path_is_not_double_encoded1(make_request):
     req = make_request('get', "http://0.0.0.0/get/test case")
-    assert req.path == "/get/test%20case"
+    assert req.url.raw_path == "/get/test%20case"
 
 
 def test_path_is_not_double_encoded2(make_request):
     req = make_request('get', "http://0.0.0.0/get/test%2fcase")
-    assert req.path == "/get/test%2fcase"
+    assert req.url.raw_path == "/get/test%2Fcase"
 
 
 def test_path_is_not_double_encoded3(make_request):
     req = make_request('get', "http://0.0.0.0/get/test%20case")
-    assert req.path == "/get/test%20case"
+    assert req.url.raw_path == "/get/test%20case"
 
 
 def test_path_safe_chars_preserved(make_request):
-    req = make_request('get', "http://0.0.0.0/get/%:=")
-    assert req.path == "/get/%:="
+    req = make_request('get', "http://0.0.0.0/get/:=")
+    assert req.url.path == "/get/:="
 
 
 def test_params_are_added_before_fragment1(make_request):
     req = make_request('GET', "http://example.com/path#fragment",
                        params={"a": "b"})
-    assert req.url == "http://example.com/path?a=b#fragment"
+    assert str(req.url) == "http://example.com/path?a=b"
 
 
 def test_params_are_added_before_fragment2(make_request):
     req = make_request('GET', "http://example.com/path?key=value#fragment",
                        params={"a": "b"})
-    assert req.url == "http://example.com/path?key=value&a=b#fragment"
+    assert str(req.url) == "http://example.com/path?key=value&a=b"
 
 
 def test_path_not_contain_fragment1(make_request):
     req = make_request('GET', "http://example.com/path#fragment")
-    assert req.path == "/path"
+    assert req.url.path == "/path"
 
 
 def test_path_not_contain_fragment2(make_request):
     req = make_request('GET', "http://example.com/path?key=value#fragment")
-    assert req.path == "/path?key=value"
+    assert str(req.url) == "http://example.com/path?key=value"
 
 
 def test_cookies(make_request):
@@ -347,19 +347,19 @@ def test_cookies_merge_with_headers(make_request):
 def test_unicode_get1(make_request):
     req = make_request('get', 'http://python.org',
                        params={'foo': 'f\xf8\xf8'})
-    assert '/?foo=f%C3%B8%C3%B8' == req.path
+    assert 'http://python.org/?foo=f%C3%B8%C3%B8' == str(req.url)
 
 
 def test_unicode_get2(make_request):
     req = make_request('', 'http://python.org',
                        params={'f\xf8\xf8': 'f\xf8\xf8'})
 
-    assert '/?f%C3%B8%C3%B8=f%C3%B8%C3%B8' == req.path
+    assert 'http://python.org/?f%C3%B8%C3%B8=f%C3%B8%C3%B8' == str(req.url)
 
 
 def test_unicode_get3(make_request):
     req = make_request('', 'http://python.org', params={'foo': 'foo'})
-    assert '/?foo=foo' == req.path
+    assert 'http://python.org/?foo=foo' == str(req.url)
 
 
 def test_unicode_get4(make_request):
@@ -367,7 +367,7 @@ def join(*suffix):
         return urllib.parse.urljoin('http://python.org/', '/'.join(suffix))
 
     req = make_request('', join('\xf8'), params={'foo': 'foo'})
-    assert '/%C3%B8?foo=foo' == req.path
+    assert 'http://python.org/%C3%B8?foo=foo' == str(req.url)
 
 
 def test_query_multivalued_param(make_request):
@@ -376,42 +376,38 @@ def test_query_multivalued_param(make_request):
             meth, 'http://python.org',
             params=(('test', 'foo'), ('test', 'baz')))
 
-        assert req.path == '/?test=foo&test=baz'
+        assert str(req.url) == 'http://python.org/?test=foo&test=baz'
 
 
 def test_query_str_param(make_request):
     for meth in ClientRequest.ALL_METHODS:
         req = make_request(meth, 'http://python.org', params='test=foo')
-        assert req.path == '/?test=foo'
+        assert str(req.url) == 'http://python.org/?test=foo'
 
 
 def test_query_bytes_param_raises(make_request):
     for meth in ClientRequest.ALL_METHODS:
-        with pytest.raises(TypeError) as ctx:
+        with pytest.raises(TypeError):
             make_request(meth, 'http://python.org', params=b'test=foo')
-        assert re.match('not a valid non-string.*or mapping', str(ctx.value))
 
 
 def test_query_str_param_is_not_encoded(make_request):
     for meth in ClientRequest.ALL_METHODS:
         req = make_request(meth, 'http://python.org', params='test=f+oo')
-        assert req.path == '/?test=f+oo'
+        assert str(req.url) == 'http://python.org/?test=f+oo'
 
 
 def test_params_update_path_and_url(make_request):
     req = make_request('get', 'http://python.org',
                        params=(('test', 'foo'), ('test', 'baz')))
-    assert req.path == '/?test=foo&test=baz'
-    assert req.url == 'http://python.org/?test=foo&test=baz'
+    assert str(req.url) == 'http://python.org/?test=foo&test=baz'
 
 
 def test_params_empty_path_and_url(make_request):
     req_empty = make_request('get', 'http://python.org', params={})
-    assert req_empty.path == '/'
-    assert req_empty.url == 'http://python.org/'
+    assert str(req_empty.url) == 'http://python.org'
     req_none = make_request('get', 'http://python.org')
-    assert req_none.path == '/'
-    assert req_none.url == 'http://python.org/'
+    assert str(req_none.url) == 'http://python.org'
 
 
 def test_gen_netloc_all(make_request):
@@ -419,8 +415,8 @@ def test_gen_netloc_all(make_request):
                        'https://aiohttp:pwpwpw@' +
                        '12345678901234567890123456789' +
                        '012345678901234567890:8080')
-    assert req.netloc == '12345678901234567890123456789' +\
-                         '012345678901234567890:8080'
+    assert req.headers['HOST'] == '12345678901234567890123456789' +\
+        '012345678901234567890:8080'
 
 
 def test_gen_netloc_no_port(make_request):
@@ -428,17 +424,8 @@ def test_gen_netloc_no_port(make_request):
                        'https://aiohttp:pwpwpw@' +
                        '12345678901234567890123456789' +
                        '012345678901234567890/')
-    assert req.netloc == '12345678901234567890123456789' +\
-                         '012345678901234567890'
-
-
-def test_gen_notloc_failed(make_request):
-    with pytest.raises(ValueError) as excinfo:
-        make_request('get',
-                     'https://aiohttp:pwpwpw@' +
-                     '123456789012345678901234567890123456789' +
-                     '01234567890123456789012345/')
-        assert excinfo.value.message == "URL has an invalid label."
+    assert req.headers['HOST'] == '12345678901234567890123456789' +\
+        '012345678901234567890'
 
 
 class TestClientRequest(unittest.TestCase):
@@ -465,35 +452,35 @@ def tearDown(self):
         gc.collect()
 
     def test_no_content_length(self):
-        req = ClientRequest('get', 'http://python.org', loop=self.loop)
+        req = ClientRequest('get', URL('http://python.org'), loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertEqual('0', req.headers.get('CONTENT-LENGTH'))
         self.loop.run_until_complete(req.close())
         resp.close()
 
     def test_no_content_length2(self):
-        req = ClientRequest('head', 'http://python.org', loop=self.loop)
+        req = ClientRequest('head', URL('http://python.org'), loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertEqual('0', req.headers.get('CONTENT-LENGTH'))
         self.loop.run_until_complete(req.close())
         resp.close()
 
     def test_content_type_auto_header_get(self):
-        req = ClientRequest('get', 'http://python.org', loop=self.loop)
+        req = ClientRequest('get', URL('http://python.org'), loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertNotIn('CONTENT-TYPE', req.headers)
         resp.close()
 
     def test_content_type_auto_header_form(self):
-        req = ClientRequest('post', 'http://python.org', data={'hey': 'you'},
-                            loop=self.loop)
+        req = ClientRequest('post', URL('http://python.org'),
+                            data={'hey': 'you'}, loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertEqual('application/x-www-form-urlencoded',
                          req.headers.get('CONTENT-TYPE'))
         resp.close()
 
     def test_content_type_auto_header_bytes(self):
-        req = ClientRequest('post', 'http://python.org', data=b'hey you',
+        req = ClientRequest('post', URL('http://python.org'), data=b'hey you',
                             loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertEqual('application/octet-stream',
@@ -501,7 +488,7 @@ def test_content_type_auto_header_bytes(self):
         resp.close()
 
     def test_content_type_skip_auto_header_bytes(self):
-        req = ClientRequest('post', 'http://python.org', data=b'hey you',
+        req = ClientRequest('post', URL('http://python.org'), data=b'hey you',
                             skip_auto_headers={'Content-Type'},
                             loop=self.loop)
         resp = req.send(self.transport, self.protocol)
@@ -509,14 +496,15 @@ def test_content_type_skip_auto_header_bytes(self):
         resp.close()
 
     def test_content_type_skip_auto_header_form(self):
-        req = ClientRequest('post', 'http://python.org', data={'hey': 'you'},
-                            loop=self.loop, skip_auto_headers={'Content-Type'})
+        req = ClientRequest('post', URL('http://python.org'),
+                            data={'hey': 'you'}, loop=self.loop,
+                            skip_auto_headers={'Content-Type'})
         resp = req.send(self.transport, self.protocol)
         self.assertNotIn('CONTENT-TYPE', req.headers)
         resp.close()
 
     def test_content_type_auto_header_content_length_no_skip(self):
-        req = ClientRequest('get', 'http://python.org',
+        req = ClientRequest('get', URL('http://python.org'),
                             data=io.BytesIO(b'hey'),
                             skip_auto_headers={'Content-Length'},
                             loop=self.loop)
@@ -527,10 +515,10 @@ def test_content_type_auto_header_content_length_no_skip(self):
     def test_post_data(self):
         for meth in ClientRequest.POST_METHODS:
             req = ClientRequest(
-                meth, 'http://python.org/',
+                meth, URL('http://python.org/'),
                 data={'life': '42'}, loop=self.loop)
             resp = req.send(self.transport, self.protocol)
-            self.assertEqual('/', req.path)
+            self.assertEqual('/', req.url.path)
             self.assertEqual(b'life=42', req.body)
             self.assertEqual('application/x-www-form-urlencoded',
                              req.headers['CONTENT-TYPE'])
@@ -541,7 +529,7 @@ def test_post_data(self):
         'aiohttp.client_reqrep.ClientRequest.update_body_from_data')
     def test_pass_falsy_data(self, _):
         req = ClientRequest(
-            'post', 'http://python.org/',
+            'post', URL('http://python.org/'),
             data={}, loop=self.loop)
         req.update_body_from_data.assert_called_once_with({}, frozenset())
         self.loop.run_until_complete(req.close())
@@ -549,19 +537,19 @@ def test_pass_falsy_data(self, _):
     def test_get_with_data(self):
         for meth in ClientRequest.GET_METHODS:
             req = ClientRequest(
-                meth, 'http://python.org/', data={'life': '42'},
+                meth, URL('http://python.org/'), data={'life': '42'},
                 loop=self.loop)
-            self.assertEqual('/', req.path)
+            self.assertEqual('/', req.url.path)
             self.assertEqual(b'life=42', req.body)
             self.loop.run_until_complete(req.close())
 
     def test_bytes_data(self):
         for meth in ClientRequest.POST_METHODS:
             req = ClientRequest(
-                meth, 'http://python.org/',
+                meth, URL('http://python.org/'),
                 data=b'binary data', loop=self.loop)
             resp = req.send(self.transport, self.protocol)
-            self.assertEqual('/', req.path)
+            self.assertEqual('/', req.url.path)
             self.assertEqual(b'binary data', req.body)
             self.assertEqual('application/octet-stream',
                              req.headers['CONTENT-TYPE'])
@@ -570,7 +558,7 @@ def test_bytes_data(self):
 
     @mock.patch('aiohttp.client_reqrep.aiohttp')
     def test_content_encoding(self, m_http):
-        req = ClientRequest('get', 'http://python.org/', data='foo',
+        req = ClientRequest('get', URL('http://python.org/'), data='foo',
                             compress='deflate', loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertEqual(req.headers['TRANSFER-ENCODING'], 'chunked')
@@ -582,7 +570,7 @@ def test_content_encoding(self, m_http):
 
     @mock.patch('aiohttp.client_reqrep.aiohttp')
     def test_content_encoding_dont_set_headers_if_no_body(self, m_http):
-        req = ClientRequest('get', 'http://python.org/',
+        req = ClientRequest('get', URL('http://python.org/'),
                             compress='deflate', loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertNotIn('TRANSFER-ENCODING', req.headers)
@@ -593,7 +581,7 @@ def test_content_encoding_dont_set_headers_if_no_body(self, m_http):
     @mock.patch('aiohttp.client_reqrep.aiohttp')
     def test_content_encoding_header(self, m_http):
         req = ClientRequest(
-            'get', 'http://python.org/', data='foo',
+            'get', URL('http://python.org/'), data='foo',
             headers={'Content-Encoding': 'deflate'}, loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertEqual(req.headers['TRANSFER-ENCODING'], 'chunked')
@@ -608,7 +596,7 @@ def test_content_encoding_header(self, m_http):
 
     def test_chunked(self):
         req = ClientRequest(
-            'get', 'http://python.org/',
+            'get', URL('http://python.org/'),
             headers={'TRANSFER-ENCODING': 'gzip'}, loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertEqual('gzip', req.headers['TRANSFER-ENCODING'])
@@ -616,7 +604,7 @@ def test_chunked(self):
         resp.close()
 
         req = ClientRequest(
-            'get', 'http://python.org/',
+            'get', URL('http://python.org/'),
             headers={'Transfer-encoding': 'chunked'}, loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertEqual('chunked', req.headers['TRANSFER-ENCODING'])
@@ -626,7 +614,7 @@ def test_chunked(self):
     @mock.patch('aiohttp.client_reqrep.aiohttp')
     def test_chunked_explicit(self, m_http):
         req = ClientRequest(
-            'get', 'http://python.org/', chunked=True, loop=self.loop)
+            'get', URL('http://python.org/'), chunked=True, loop=self.loop)
         resp = req.send(self.transport, self.protocol)
 
         self.assertEqual('chunked', req.headers['TRANSFER-ENCODING'])
@@ -638,7 +626,7 @@ def test_chunked_explicit(self, m_http):
     @mock.patch('aiohttp.client_reqrep.aiohttp')
     def test_chunked_explicit_size(self, m_http):
         req = ClientRequest(
-            'get', 'http://python.org/', chunked=1024, loop=self.loop)
+            'get', URL('http://python.org/'), chunked=1024, loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertEqual('chunked', req.headers['TRANSFER-ENCODING'])
         m_http.Request.return_value\
@@ -648,7 +636,7 @@ def test_chunked_explicit_size(self, m_http):
 
     def test_chunked_length(self):
         req = ClientRequest(
-            'get', 'http://python.org/',
+            'get', URL('http://python.org/'),
             headers={'CONTENT-LENGTH': '1000'}, chunked=1024, loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertEqual(req.headers['TRANSFER-ENCODING'], 'chunked')
@@ -661,7 +649,7 @@ def test_file_upload_not_chunked(self):
         fname = os.path.join(here, 'sample.key')
         with open(fname, 'rb') as f:
             req = ClientRequest(
-                'post', 'http://python.org/',
+                'post', URL('http://python.org/'),
                 data=f,
                 loop=self.loop)
             self.assertFalse(req.chunked)
@@ -672,7 +660,7 @@ def test_file_upload_not_chunked(self):
     def test_precompressed_data_stays_intact(self):
         data = zlib.compress(b'foobar')
         req = ClientRequest(
-            'post', 'http://python.org/',
+            'post', URL('http://python.org/'),
             data=data,
             headers={'CONTENT-ENCODING': 'deflate'},
             compress=False,
@@ -689,7 +677,7 @@ def test_file_upload_not_chunked_seek(self):
         with open(fname, 'rb') as f:
             f.seek(100)
             req = ClientRequest(
-                'post', 'http://python.org/',
+                'post', URL('http://python.org/'),
                 data=f,
                 loop=self.loop)
             self.assertEqual(req.headers['CONTENT-LENGTH'],
@@ -701,7 +689,7 @@ def test_file_upload_force_chunked(self):
         fname = os.path.join(here, 'sample.key')
         with open(fname, 'rb') as f:
             req = ClientRequest(
-                'post', 'http://python.org/',
+                'post', URL('http://python.org/'),
                 data=f,
                 chunked=True,
                 loop=self.loop)
@@ -710,7 +698,7 @@ def test_file_upload_force_chunked(self):
             self.loop.run_until_complete(req.close())
 
     def test_expect100(self):
-        req = ClientRequest('get', 'http://python.org/',
+        req = ClientRequest('get', URL('http://python.org/'),
                             expect100=True, loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertEqual('100-continue', req.headers['EXPECT'])
@@ -719,7 +707,7 @@ def test_expect100(self):
         resp.close()
 
     def test_expect_100_continue_header(self):
-        req = ClientRequest('get', 'http://python.org/',
+        req = ClientRequest('get', URL('http://python.org/'),
                             headers={'expect': '100-continue'}, loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertEqual('100-continue', req.headers['EXPECT'])
@@ -733,7 +721,7 @@ def gen():
             return b' result'
 
         req = ClientRequest(
-            'POST', 'http://python.org/', data=gen(), loop=self.loop)
+            'POST', URL('http://python.org/'), data=gen(), loop=self.loop)
         self.assertTrue(req.chunked)
         self.assertTrue(inspect.isgenerator(req.body))
         self.assertEqual(req.headers['TRANSFER-ENCODING'], 'chunked')
@@ -750,7 +738,7 @@ def gen():
 
     def test_data_file(self):
         req = ClientRequest(
-            'POST', 'http://python.org/',
+            'POST', URL('http://python.org/'),
             data=io.BufferedReader(io.BytesIO(b'*' * 2)),
             loop=self.loop)
         self.assertTrue(req.chunked)
@@ -775,7 +763,7 @@ def gen():
             yield from fut
 
         req = ClientRequest(
-            'POST', 'http://python.org/', data=gen(), loop=self.loop)
+            'POST', URL('http://python.org/'), data=gen(), loop=self.loop)
         self.assertTrue(req.chunked)
         self.assertTrue(inspect.isgenerator(req.body))
         self.assertEqual(req.headers['TRANSFER-ENCODING'], 'chunked')
@@ -800,7 +788,7 @@ def gen():
             yield object()
 
         req = ClientRequest(
-            'POST', 'http://python.org/', data=gen(), loop=self.loop)
+            'POST', URL('http://python.org/'), data=gen(), loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.loop.run_until_complete(req._writer)
         self.assertTrue(self.protocol.set_exception.called)
@@ -814,7 +802,7 @@ def gen():
             yield from fut
 
         req = ClientRequest(
-            'POST', 'http://python.org/', data=gen(), loop=self.loop)
+            'POST', URL('http://python.org/'), data=gen(), loop=self.loop)
 
         inner_exc = ValueError()
 
@@ -842,7 +830,7 @@ def gen():
             return b' result'
 
         req = ClientRequest(
-            'POST', 'http://python.org/', data=gen(),
+            'POST', URL('http://python.org/'), data=gen(),
             expect100=True, loop=self.loop)
         self.assertTrue(req.chunked)
         self.assertTrue(inspect.isgenerator(req.body))
@@ -864,7 +852,7 @@ def coro():
 
     def test_data_continue(self):
         req = ClientRequest(
-            'POST', 'http://python.org/', data=b'data',
+            'POST', URL('http://python.org/'), data=b'data',
             expect100=True, loop=self.loop)
 
         def coro():
@@ -890,7 +878,7 @@ def gen():
             return b'result'
 
         req = ClientRequest(
-            'POST', 'http://python.org/', data=gen(), loop=self.loop)
+            'POST', URL('http://python.org/'), data=gen(), loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.loop.run_until_complete(req.close())
         self.assertEqual(
@@ -906,7 +894,7 @@ def read(self, decode=False):
                 return 'customized!'
 
         req = ClientRequest(
-            'GET', 'http://python.org/', response_class=CustomResponse,
+            'GET', URL('http://python.org/'), response_class=CustomResponse,
             loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertEqual('customized!', resp.read())
@@ -914,7 +902,7 @@ def read(self, decode=False):
         resp.close()
 
     def test_terminate(self):
-        req = ClientRequest('get', 'http://python.org', loop=self.loop)
+        req = ClientRequest('get', URL('http://python.org'), loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertIsNotNone(req._writer)
         writer = req._writer = mock.Mock()
@@ -925,7 +913,7 @@ def test_terminate(self):
         resp.close()
 
     def test_terminate_with_closed_loop(self):
-        req = ClientRequest('get', 'http://python.org', loop=self.loop)
+        req = ClientRequest('get', URL('http://python.org'), loop=self.loop)
         resp = req.send(self.transport, self.protocol)
         self.assertIsNotNone(req._writer)
         writer = req._writer = mock.Mock()
@@ -937,7 +925,7 @@ def test_terminate_with_closed_loop(self):
         resp.close()
 
     def test_terminate_without_writer(self):
-        req = ClientRequest('get', 'http://python.org', loop=self.loop)
+        req = ClientRequest('get', URL('http://python.org'), loop=self.loop)
         self.assertIsNone(req._writer)
 
         req.terminate()
@@ -981,12 +969,13 @@ def create_connection(req):
                 return self.transport, self.protocol
             self.connector._create_connection = create_connection
 
-            resp = yield from aiohttp.request('get',
-                                              'http://example.com/path/to',
-                                              request_class=CustomRequest,
-                                              response_class=CustomResponse,
-                                              connector=self.connector,
-                                              loop=self.loop)
+            resp = yield from aiohttp.request(
+                'get',
+                URL('http://example.com/path/to'),
+                request_class=CustomRequest,
+                response_class=CustomResponse,
+                connector=self.connector,
+                loop=self.loop)
             self.assertIsInstance(resp, CustomResponse)
             self.assertTrue(called)
             resp.close()
diff --git a/tests/test_client_response.py b/tests/test_client_response.py
index ce46478f037..7ed6e426ee5 100644
--- a/tests/test_client_response.py
+++ b/tests/test_client_response.py
@@ -6,6 +6,8 @@
 import unittest
 from unittest import mock
 
+from yarl import URL
+
 import aiohttp
 from aiohttp import helpers
 from aiohttp.client_reqrep import ClientResponse
@@ -19,7 +21,7 @@ def setUp(self):
 
         self.connection = mock.Mock()
         self.stream = aiohttp.StreamParser(loop=self.loop)
-        self.response = ClientResponse('get', 'http://def-cl-resp.org')
+        self.response = ClientResponse('get', URL('http://def-cl-resp.org'))
         self.response._post_init(self.loop)
         self.response._setup_connection(self.connection)
 
@@ -29,7 +31,7 @@ def tearDown(self):
         gc.collect()
 
     def test_del(self):
-        response = ClientResponse('get', 'http://del-cl-resp.org')
+        response = ClientResponse('get', URL('http://del-cl-resp.org'))
         response._post_init(self.loop)
 
         connection = mock.Mock()
@@ -51,14 +53,14 @@ def test_close(self):
 
     def test_wait_for_100_1(self):
         response = ClientResponse(
-            'get', 'http://python.org', continue100=object())
+            'get', URL('http://python.org'), continue100=object())
         response._post_init(self.loop)
         self.assertTrue(response.waiting_for_continue())
         response.close()
 
     def test_wait_for_100_2(self):
         response = ClientResponse(
-            'get', 'http://python.org')
+            'get', URL('http://python.org'))
         response._post_init(self.loop)
         self.assertFalse(response.waiting_for_continue())
         response.close()
@@ -71,13 +73,13 @@ def test_repr(self):
             repr(self.response))
 
     def test_repr_non_ascii_url(self):
-        response = ClientResponse('get', 'http://fake-host.org/\u03bb')
+        response = ClientResponse('get', URL('http://fake-host.org/\u03bb'))
         self.assertIn(
-            "<ClientResponse(http://fake-host.org/\\u03bb) [None None]>",
+            "<ClientResponse(http://fake-host.org/%CE%BB) [None None]>",
             repr(response))
 
     def test_repr_non_ascii_reason(self):
-        response = ClientResponse('get', 'http://fake-host.org/path')
+        response = ClientResponse('get', URL('http://fake-host.org/path'))
         response.reason = '\u03bb'
         self.assertIn(
             "<ClientResponse(http://fake-host.org/path) [None \\u03bb]>",
@@ -243,7 +245,7 @@ def side_effect(*args, **kwargs):
     def test_override_flow_control(self):
         class MyResponse(ClientResponse):
             flow_control_class = aiohttp.StreamReader
-        response = MyResponse('get', 'http://my-cl-resp.org')
+        response = MyResponse('get', URL('http://my-cl-resp.org'))
         response._post_init(self.loop)
         response._setup_connection(self.connection)
         self.assertIsInstance(response.content, aiohttp.StreamReader)
diff --git a/tests/test_client_session.py b/tests/test_client_session.py
index c9455611e0f..efd34faf5c8 100644
--- a/tests/test_client_session.py
+++ b/tests/test_client_session.py
@@ -8,6 +8,7 @@
 
 import pytest
 from multidict import CIMultiDict, MultiDict
+from yarl import URL
 
 import aiohttp
 from aiohttp import web
@@ -94,7 +95,7 @@ def test_init_headers_list_of_tuples_with_duplicates(create_session):
 def test_init_cookies_with_simple_dict(create_session):
     session = create_session(cookies={"c1": "cookie1",
                                       "c2": "cookie2"})
-    cookies = session.cookie_jar.filter_cookies('')
+    cookies = session.cookie_jar.filter_cookies()
     assert set(cookies) == {'c1', 'c2'}
     assert cookies['c1'].value == 'cookie1'
     assert cookies['c2'].value == 'cookie2'
@@ -104,7 +105,7 @@ def test_init_cookies_with_list_of_tuples(create_session):
     session = create_session(cookies=[("c1", "cookie1"),
                                       ("c2", "cookie2")])
 
-    cookies = session.cookie_jar.filter_cookies('')
+    cookies = session.cookie_jar.filter_cookies()
     assert set(cookies) == {'c1', 'c2'}
     assert cookies['c1'].value == 'cookie1'
     assert cookies['c2'].value == 'cookie2'
@@ -402,7 +403,7 @@ def handler(request):
 
     # Filtering the cookie jar before sending the request,
     # getting the request URL as only parameter
-    jar.filter_cookies.assert_called_with(req_url)
+    jar.filter_cookies.assert_called_with(URL(req_url))
 
     # Updating the cookie jar with the response cookies
     assert jar.update_cookies.called
@@ -420,3 +421,16 @@ def test_session_default_version(loop):
 def test_session_loop(loop):
     session = aiohttp.ClientSession(loop=loop)
     assert session.loop is loop
+
+
+def test_proxy_str(session, params):
+    with mock.patch("aiohttp.client.ClientSession._request") as patched:
+        session.get("http://test.example.com",
+                    proxy='http://proxy.com',
+                    **params)
+    assert patched.called, "`ClientSession._request` not called"
+    assert list(patched.call_args) == [("GET", "http://test.example.com",),
+                                       dict(
+                                           allow_redirects=True,
+                                           proxy='http://proxy.com',
+                                           **params)]
diff --git a/tests/test_connector.py b/tests/test_connector.py
index 6ed6f4aa694..4a9039dc0f9 100644
--- a/tests/test_connector.py
+++ b/tests/test_connector.py
@@ -12,6 +12,8 @@
 
 import pytest
 
+from yarl import URL
+
 import aiohttp
 from aiohttp import client, helpers, web
 from aiohttp.client import ClientRequest
@@ -287,7 +289,7 @@ def test_connect(loop):
     tr, proto = unittest.mock.Mock(), unittest.mock.Mock()
     proto.is_connected.return_value = True
 
-    req = ClientRequest('GET', 'http://host:80',
+    req = ClientRequest('GET', URL('http://host:80'),
                         loop=loop,
                         response_class=unittest.mock.Mock())
 
@@ -526,7 +528,7 @@ def test_connect_with_limit(loop):
     tr, proto = unittest.mock.Mock(), unittest.mock.Mock()
     proto.is_connected.return_value = True
 
-    req = ClientRequest('GET', 'http://host:80',
+    req = ClientRequest('GET', URL('http://host:80'),
                         loop=loop,
                         response_class=unittest.mock.Mock())
 
@@ -569,7 +571,7 @@ def test_connect_with_limit_cancelled(loop):
     tr, proto = unittest.mock.Mock(), unittest.mock.Mock()
     proto.is_connected.return_value = True
 
-    req = ClientRequest('GET', 'http://host:80',
+    req = ClientRequest('GET', URL('http://host:80'),
                         loop=loop,
                         response_class=unittest.mock.Mock())
 
@@ -618,7 +620,7 @@ def test_connect_with_limit_concurrent(loop):
     proto = unittest.mock.Mock()
     proto.is_connected.return_value = True
 
-    req = ClientRequest('GET', 'http://host:80',
+    req = ClientRequest('GET', URL('http://host:80'),
                         loop=loop,
                         response_class=unittest.mock.Mock(
                             _should_close=False))
@@ -684,7 +686,7 @@ def test_close_with_acquired_connection(loop):
     tr, proto = unittest.mock.Mock(), unittest.mock.Mock()
     proto.is_connected.return_value = True
 
-    req = ClientRequest('GET', 'http://host:80',
+    req = ClientRequest('GET', URL('http://host:80'),
                         loop=loop,
                         response_class=unittest.mock.Mock())
 
@@ -878,7 +880,8 @@ def test_resolver_not_called_with_address_is_ip(self):
         resolver = unittest.mock.MagicMock()
         connector = aiohttp.TCPConnector(resolver=resolver, loop=self.loop)
 
-        req = ClientRequest('GET', 'http://127.0.0.1:{}'.format(unused_port()),
+        req = ClientRequest('GET',
+                            URL('http://127.0.0.1:{}'.format(unused_port())),
                             loop=self.loop,
                             response_class=unittest.mock.Mock())
 
diff --git a/tests/test_cookiejar.py b/tests/test_cookiejar.py
index 359fb63d2f7..4d86e86383a 100644
--- a/tests/test_cookiejar.py
+++ b/tests/test_cookiejar.py
@@ -6,6 +6,8 @@
 
 import pytest
 
+from yarl import URL
+
 from aiohttp import CookieJar
 
 
@@ -172,7 +174,7 @@ def test_domain_filter_ip_cookie_send(loop):
     )
 
     jar.update_cookies(cookies)
-    cookies_sent = jar.filter_cookies("http://1.2.3.4/").output(
+    cookies_sent = jar.filter_cookies(URL("http://1.2.3.4/")).output(
         header='Cookie:')
     assert cookies_sent == 'Cookie: shared-cookie=first'
 
@@ -180,7 +182,7 @@ def test_domain_filter_ip_cookie_send(loop):
 def test_domain_filter_ip_cookie_receive(loop, cookies_to_receive):
     jar = CookieJar(loop=loop)
 
-    jar.update_cookies(cookies_to_receive, "http://1.2.3.4/")
+    jar.update_cookies(cookies_to_receive, URL("http://1.2.3.4/"))
     assert len(jar) == 0
 
 
@@ -190,7 +192,7 @@ def test_preserving_ip_domain_cookies(loop):
         "shared-cookie=first; "
         "ip-cookie=second; Domain=127.0.0.1;"
     ))
-    cookies_sent = jar.filter_cookies("http://127.0.0.1/").output(
+    cookies_sent = jar.filter_cookies(URL("http://127.0.0.1/")).output(
         header='Cookie:')
     assert cookies_sent == ('Cookie: ip-cookie=second\r\n'
                             'Cookie: shared-cookie=first')
@@ -199,10 +201,10 @@ def test_preserving_ip_domain_cookies(loop):
 def test_ignore_domain_ending_with_dot(loop):
     jar = CookieJar(loop=loop, unsafe=True)
     jar.update_cookies(SimpleCookie("cookie=val; Domain=example.com.;"),
-                       "http://www.example.com")
-    cookies_sent = jar.filter_cookies("http://www.example.com/")
+                       URL("http://www.example.com"))
+    cookies_sent = jar.filter_cookies(URL("http://www.example.com/"))
     assert cookies_sent.output(header='Cookie:') == "Cookie: cookie=val"
-    cookies_sent = jar.filter_cookies("http://example.com/")
+    cookies_sent = jar.filter_cookies(URL("http://example.com/"))
     assert cookies_sent.output(header='Cookie:') == ""
 
 
@@ -220,11 +222,11 @@ def tearDown(self):
 
     def request_reply_with_same_url(self, url):
         self.jar.update_cookies(self.cookies_to_send)
-        cookies_sent = self.jar.filter_cookies(url)
+        cookies_sent = self.jar.filter_cookies(URL(url))
 
         self.jar.clear()
 
-        self.jar.update_cookies(self.cookies_to_receive, url)
+        self.jar.update_cookies(self.cookies_to_receive, URL(url))
         cookies_received = SimpleCookie()
         for cookie in self.jar:
             dict.__setitem__(cookies_received, cookie.key, cookie)
@@ -281,7 +283,7 @@ def timed_request(self, url, update_time, send_time):
             self.jar.update_cookies(self.cookies_to_send)
 
         with mock.patch.object(self.loop, 'time', return_value=send_time):
-            cookies_sent = self.jar.filter_cookies(url)
+            cookies_sent = self.jar.filter_cookies(URL(url))
 
         self.jar.clear()
 
@@ -352,12 +354,13 @@ def test_domain_filter_diff_host(self):
         })
 
     def test_domain_filter_host_only(self):
-        self.jar.update_cookies(self.cookies_to_receive, "http://example.com/")
+        self.jar.update_cookies(self.cookies_to_receive,
+                                URL("http://example.com/"))
 
-        cookies_sent = self.jar.filter_cookies("http://example.com/")
+        cookies_sent = self.jar.filter_cookies(URL("http://example.com/"))
         self.assertIn("unconstrained-cookie", set(cookies_sent.keys()))
 
-        cookies_sent = self.jar.filter_cookies("http://different.org/")
+        cookies_sent = self.jar.filter_cookies(URL("http://different.org/"))
         self.assertNotIn("unconstrained-cookie", set(cookies_sent.keys()))
 
     def test_secure_filter(self):
diff --git a/tests/test_helpers.py b/tests/test_helpers.py
index 202ff1e7d58..582c7d56389 100644
--- a/tests/test_helpers.py
+++ b/tests/test_helpers.py
@@ -233,19 +233,6 @@ def prop(self):
         a.prop = 123
 
 
-def test_requote_uri_with_unquoted_percents():
-    # Ensure we handle unquoted percent signs in redirects.
-    bad_uri = 'http://example.com/fiz?buz=%ppicture'
-    quoted = 'http://example.com/fiz?buz=%25ppicture'
-    assert quoted == helpers.requote_uri(bad_uri)
-
-
-def test_requote_uri_properly_requotes():
-    # Ensure requoting doesn't break expectations.
-    quoted = 'http://example.com/fiz?buz=%25ppicture'
-    assert quoted == helpers.requote_uri(quoted)
-
-
 def test_create_future_with_new_loop():
     # We should use the new create_future() if it's available.
     mock_loop = mock.Mock()
diff --git a/tests/test_proxy.py b/tests/test_proxy.py
index deff66e0ee3..7b27d42a368 100644
--- a/tests/test_proxy.py
+++ b/tests/test_proxy.py
@@ -4,6 +4,8 @@
 import unittest
 from unittest import mock
 
+from yarl import URL
+
 import aiohttp
 from aiohttp.client_reqrep import ClientRequest, ClientResponse
 from aiohttp.test_utils import make_mocked_coro
@@ -25,11 +27,11 @@ def tearDown(self):
     @mock.patch('aiohttp.connector.ClientRequest')
     def test_connect(self, ClientRequestMock):
         req = ClientRequest(
-            'GET', 'http://www.python.org',
-            proxy='http://proxy.example.com',
+            'GET', URL('http://www.python.org'),
+            proxy=URL('http://proxy.example.com'),
             loop=self.loop
         )
-        self.assertEqual(req.proxy, 'http://proxy.example.com')
+        self.assertEqual(str(req.proxy), 'http://proxy.example.com')
 
         # mock all the things!
         connector = aiohttp.TCPConnector(loop=self.loop)
@@ -38,12 +40,12 @@ def test_connect(self, ClientRequestMock):
         tr, proto = mock.Mock(), mock.Mock()
         self.loop.create_connection = make_mocked_coro((tr, proto))
         conn = self.loop.run_until_complete(connector.connect(req))
-        self.assertEqual(req.path, 'http://www.python.org/')
+        self.assertEqual(req.path, 'http://www.python.org')
         self.assertIs(conn._transport, tr)
         self.assertIs(conn._protocol, proto)
 
         ClientRequestMock.assert_called_with(
-            'GET', 'http://proxy.example.com',
+            'GET', URL('http://proxy.example.com'),
             auth=None,
             headers={'Host': 'www.python.org'},
             loop=self.loop)
@@ -51,8 +53,8 @@ def test_connect(self, ClientRequestMock):
     def test_proxy_auth(self):
         with self.assertRaises(ValueError) as ctx:
             ClientRequest(
-                'GET', 'http://python.org',
-                proxy='http://proxy.example.com',
+                'GET', URL('http://python.org'),
+                proxy=URL('http://proxy.example.com'),
                 proxy_auth=('user', 'pass'),
                 loop=mock.Mock())
         self.assertEqual(
@@ -66,20 +68,20 @@ def test_proxy_connection_error(self):
             raise_exception=OSError('dont take it serious'))
 
         req = ClientRequest(
-            'GET', 'http://www.python.org',
-            proxy='http://proxy.example.com',
+            'GET', URL('http://www.python.org'),
+            proxy=URL('http://proxy.example.com'),
             loop=self.loop,
         )
         expected_headers = dict(req.headers)
         with self.assertRaises(aiohttp.ProxyConnectionError):
             self.loop.run_until_complete(connector.connect(req))
-        self.assertEqual(req.path, '/')
+        self.assertEqual(req.url.path, '/')
         self.assertEqual(dict(req.headers), expected_headers)
 
     @mock.patch('aiohttp.connector.ClientRequest')
     def test_auth(self, ClientRequestMock):
         proxy_req = ClientRequest(
-            'GET', 'http://proxy.example.com',
+            'GET', URL('http://proxy.example.com'),
             auth=aiohttp.helpers.BasicAuth('user', 'pass'),
             loop=self.loop
         )
@@ -94,8 +96,8 @@ def test_auth(self, ClientRequestMock):
         self.loop.create_connection = make_mocked_coro((tr, proto))
 
         req = ClientRequest(
-            'GET', 'http://www.python.org',
-            proxy='http://proxy.example.com',
+            'GET', URL('http://www.python.org'),
+            proxy=URL('http://proxy.example.com'),
             proxy_auth=aiohttp.helpers.BasicAuth('user', 'pass'),
             loop=self.loop,
         )
@@ -103,28 +105,29 @@ def test_auth(self, ClientRequestMock):
         self.assertNotIn('PROXY-AUTHORIZATION', req.headers)
         conn = self.loop.run_until_complete(connector.connect(req))
 
-        self.assertEqual(req.path, 'http://www.python.org/')
+        self.assertEqual(req.path, 'http://www.python.org')
         self.assertNotIn('AUTHORIZATION', req.headers)
         self.assertIn('PROXY-AUTHORIZATION', req.headers)
         self.assertNotIn('AUTHORIZATION', proxy_req.headers)
         self.assertNotIn('PROXY-AUTHORIZATION', proxy_req.headers)
 
         ClientRequestMock.assert_called_with(
-            'GET', 'http://proxy.example.com',
+            'GET', URL('http://proxy.example.com'),
             auth=aiohttp.helpers.BasicAuth('user', 'pass'),
             loop=mock.ANY, headers=mock.ANY)
         conn.close()
 
     def test_auth_utf8(self):
         proxy_req = ClientRequest(
-            'GET', 'http://proxy.example.com',
+            'GET', URL('http://proxy.example.com'),
             auth=aiohttp.helpers.BasicAuth('юзер', 'пасс', 'utf-8'),
             loop=self.loop)
         self.assertIn('AUTHORIZATION', proxy_req.headers)
 
     @mock.patch('aiohttp.connector.ClientRequest')
     def test_auth_from_url(self, ClientRequestMock):
-        proxy_req = ClientRequest('GET', 'http://user:pass@proxy.example.com',
+        proxy_req = ClientRequest('GET',
+                                  URL('http://user:pass@proxy.example.com'),
                                   loop=self.loop)
         ClientRequestMock.return_value = proxy_req
         self.assertIn('AUTHORIZATION', proxy_req.headers)
@@ -137,28 +140,29 @@ def test_auth_from_url(self, ClientRequestMock):
         self.loop.create_connection = make_mocked_coro((tr, proto))
 
         req = ClientRequest(
-            'GET', 'http://www.python.org',
-            proxy='http://user:pass@proxy.example.com',
+            'GET', URL('http://www.python.org'),
+            proxy=URL('http://user:pass@proxy.example.com'),
             loop=self.loop,
         )
         self.assertNotIn('AUTHORIZATION', req.headers)
         self.assertNotIn('PROXY-AUTHORIZATION', req.headers)
         conn = self.loop.run_until_complete(connector.connect(req))
 
-        self.assertEqual(req.path, 'http://www.python.org/')
+        self.assertEqual(req.path, 'http://www.python.org')
         self.assertNotIn('AUTHORIZATION', req.headers)
         self.assertIn('PROXY-AUTHORIZATION', req.headers)
         self.assertNotIn('AUTHORIZATION', proxy_req.headers)
         self.assertNotIn('PROXY-AUTHORIZATION', proxy_req.headers)
 
         ClientRequestMock.assert_called_with(
-            'GET', 'http://user:pass@proxy.example.com',
+            'GET', URL('http://user:pass@proxy.example.com'),
             auth=None, loop=mock.ANY, headers=mock.ANY)
         conn.close()
 
     @mock.patch('aiohttp.connector.ClientRequest')
     def test_auth__not_modifying_request(self, ClientRequestMock):
-        proxy_req = ClientRequest('GET', 'http://user:pass@proxy.example.com',
+        proxy_req = ClientRequest('GET',
+                                  URL('http://user:pass@proxy.example.com'),
                                   loop=self.loop)
         ClientRequestMock.return_value = proxy_req
         proxy_req_headers = dict(proxy_req.headers)
@@ -168,24 +172,24 @@ def test_auth__not_modifying_request(self, ClientRequestMock):
             raise_exception=OSError('nothing personal'))
 
         req = ClientRequest(
-            'GET', 'http://www.python.org',
-            proxy='http://user:pass@proxy.example.com',
+            'GET', URL('http://www.python.org'),
+            proxy=URL('http://user:pass@proxy.example.com'),
             loop=self.loop,
         )
         req_headers = dict(req.headers)
         with self.assertRaises(aiohttp.ProxyConnectionError):
             self.loop.run_until_complete(connector.connect(req))
         self.assertEqual(req.headers, req_headers)
-        self.assertEqual(req.path, '/')
+        self.assertEqual(req.url.path, '/')
         self.assertEqual(proxy_req.headers, proxy_req_headers)
 
     @mock.patch('aiohttp.connector.ClientRequest')
     def test_https_connect(self, ClientRequestMock):
-        proxy_req = ClientRequest('GET', 'http://proxy.example.com',
+        proxy_req = ClientRequest('GET', URL('http://proxy.example.com'),
                                   loop=self.loop)
         ClientRequestMock.return_value = proxy_req
 
-        proxy_resp = ClientResponse('get', 'http://proxy.example.com')
+        proxy_resp = ClientResponse('get', URL('http://proxy.example.com'))
         proxy_resp._loop = self.loop
         proxy_req.send = send_mock = mock.Mock()
         send_mock.return_value = proxy_resp
@@ -200,13 +204,13 @@ def test_https_connect(self, ClientRequestMock):
         self.loop.create_connection = make_mocked_coro((tr, proto))
 
         req = ClientRequest(
-            'GET', 'https://www.python.org',
-            proxy='http://proxy.example.com',
+            'GET', URL('https://www.python.org'),
+            proxy=URL('http://proxy.example.com'),
             loop=self.loop,
         )
         self.loop.run_until_complete(connector._create_connection(req))
 
-        self.assertEqual(req.path, '/')
+        self.assertEqual(req.url.path, '/')
         self.assertEqual(proxy_req.method, 'CONNECT')
         self.assertEqual(proxy_req.path, 'www.python.org:443')
         tr.pause_reading.assert_called_once_with()
@@ -218,11 +222,11 @@ def test_https_connect(self, ClientRequestMock):
 
     @mock.patch('aiohttp.connector.ClientRequest')
     def test_https_connect_runtime_error(self, ClientRequestMock):
-        proxy_req = ClientRequest('GET', 'http://proxy.example.com',
+        proxy_req = ClientRequest('GET', URL('http://proxy.example.com'),
                                   loop=self.loop)
         ClientRequestMock.return_value = proxy_req
 
-        proxy_resp = ClientResponse('get', 'http://proxy.example.com')
+        proxy_resp = ClientResponse('get', URL('http://proxy.example.com'))
         proxy_resp._loop = self.loop
         proxy_req.send = send_mock = mock.Mock()
         send_mock.return_value = proxy_resp
@@ -238,8 +242,8 @@ def test_https_connect_runtime_error(self, ClientRequestMock):
         self.loop.create_connection = make_mocked_coro((tr, proto))
 
         req = ClientRequest(
-            'GET', 'https://www.python.org',
-            proxy='http://proxy.example.com',
+            'GET', URL('https://www.python.org'),
+            proxy=URL('http://proxy.example.com'),
             loop=self.loop,
         )
         with self.assertRaisesRegex(
@@ -252,11 +256,11 @@ def test_https_connect_runtime_error(self, ClientRequestMock):
 
     @mock.patch('aiohttp.connector.ClientRequest')
     def test_https_connect_http_proxy_error(self, ClientRequestMock):
-        proxy_req = ClientRequest('GET', 'http://proxy.example.com',
+        proxy_req = ClientRequest('GET', URL('http://proxy.example.com'),
                                   loop=self.loop)
         ClientRequestMock.return_value = proxy_req
 
-        proxy_resp = ClientResponse('get', 'http://proxy.example.com')
+        proxy_resp = ClientResponse('get', URL('http://proxy.example.com'))
         proxy_resp._loop = self.loop
         proxy_req.send = send_mock = mock.Mock()
         send_mock.return_value = proxy_resp
@@ -274,8 +278,8 @@ def test_https_connect_http_proxy_error(self, ClientRequestMock):
         self.loop.create_connection = make_mocked_coro((tr, proto))
 
         req = ClientRequest(
-            'GET', 'https://www.python.org',
-            proxy='http://proxy.example.com',
+            'GET', URL('https://www.python.org'),
+            proxy=URL('http://proxy.example.com'),
             loop=self.loop,
         )
         with self.assertRaisesRegex(
@@ -288,11 +292,11 @@ def test_https_connect_http_proxy_error(self, ClientRequestMock):
 
     @mock.patch('aiohttp.connector.ClientRequest')
     def test_https_connect_resp_start_error(self, ClientRequestMock):
-        proxy_req = ClientRequest('GET', 'http://proxy.example.com',
+        proxy_req = ClientRequest('GET', URL('http://proxy.example.com'),
                                   loop=self.loop)
         ClientRequestMock.return_value = proxy_req
 
-        proxy_resp = ClientResponse('get', 'http://proxy.example.com')
+        proxy_resp = ClientResponse('get', URL('http://proxy.example.com'))
         proxy_resp._loop = self.loop
         proxy_req.send = send_mock = mock.Mock()
         send_mock.return_value = proxy_resp
@@ -309,8 +313,8 @@ def test_https_connect_resp_start_error(self, ClientRequestMock):
         self.loop.create_connection = make_mocked_coro((tr, proto))
 
         req = ClientRequest(
-            'GET', 'https://www.python.org',
-            proxy='http://proxy.example.com',
+            'GET', URL('https://www.python.org'),
+            proxy=URL('http://proxy.example.com'),
             loop=self.loop,
         )
         with self.assertRaisesRegex(OSError, "error message"):
@@ -318,7 +322,7 @@ def test_https_connect_resp_start_error(self, ClientRequestMock):
 
     @mock.patch('aiohttp.connector.ClientRequest')
     def test_request_port(self, ClientRequestMock):
-        proxy_req = ClientRequest('GET', 'http://proxy.example.com',
+        proxy_req = ClientRequest('GET', URL('http://proxy.example.com'),
                                   loop=self.loop)
         ClientRequestMock.return_value = proxy_req
 
@@ -332,8 +336,8 @@ def test_request_port(self, ClientRequestMock):
         self.loop.create_connection = make_mocked_coro((tr, proto))
 
         req = ClientRequest(
-            'GET', 'http://localhost:1234/path',
-            proxy='http://proxy.example.com',
+            'GET', URL('http://localhost:1234/path'),
+            proxy=URL('http://proxy.example.com'),
             loop=self.loop,
         )
         self.loop.run_until_complete(connector._create_connection(req))
@@ -341,26 +345,26 @@ def test_request_port(self, ClientRequestMock):
 
     def test_proxy_auth_property(self):
         req = aiohttp.ClientRequest(
-            'GET', 'http://localhost:1234/path',
-            proxy='http://proxy.example.com',
+            'GET', URL('http://localhost:1234/path'),
+            proxy=URL('http://proxy.example.com'),
             proxy_auth=aiohttp.helpers.BasicAuth('user', 'pass'),
             loop=self.loop)
         self.assertEqual(('user', 'pass', 'latin1'), req.proxy_auth)
 
     def test_proxy_auth_property_default(self):
         req = aiohttp.ClientRequest(
-            'GET', 'http://localhost:1234/path',
-            proxy='http://proxy.example.com',
+            'GET', URL('http://localhost:1234/path'),
+            proxy=URL('http://proxy.example.com'),
             loop=self.loop)
         self.assertIsNone(req.proxy_auth)
 
     @mock.patch('aiohttp.connector.ClientRequest')
     def test_https_connect_pass_ssl_context(self, ClientRequestMock):
-        proxy_req = ClientRequest('GET', 'http://proxy.example.com',
+        proxy_req = ClientRequest('GET', URL('http://proxy.example.com'),
                                   loop=self.loop)
         ClientRequestMock.return_value = proxy_req
 
-        proxy_resp = ClientResponse('get', 'http://proxy.example.com')
+        proxy_resp = ClientResponse('get', URL('http://proxy.example.com'))
         proxy_resp._loop = self.loop
         proxy_req.send = send_mock = mock.Mock()
         send_mock.return_value = proxy_resp
@@ -375,8 +379,8 @@ def test_https_connect_pass_ssl_context(self, ClientRequestMock):
         self.loop.create_connection = make_mocked_coro((tr, proto))
 
         req = ClientRequest(
-            'GET', 'https://www.python.org',
-            proxy='http://proxy.example.com',
+            'GET', URL('https://www.python.org'),
+            proxy=URL('http://proxy.example.com'),
             loop=self.loop,
         )
         self.loop.run_until_complete(connector._create_connection(req))
@@ -387,7 +391,7 @@ def test_https_connect_pass_ssl_context(self, ClientRequestMock):
             sock=mock.ANY,
             server_hostname='www.python.org')
 
-        self.assertEqual(req.path, '/')
+        self.assertEqual(req.url.path, '/')
         self.assertEqual(proxy_req.method, 'CONNECT')
         self.assertEqual(proxy_req.path, 'www.python.org:443')
         tr.pause_reading.assert_called_once_with()
@@ -399,13 +403,13 @@ def test_https_connect_pass_ssl_context(self, ClientRequestMock):
 
     @mock.patch('aiohttp.connector.ClientRequest')
     def test_https_auth(self, ClientRequestMock):
-        proxy_req = ClientRequest('GET', 'http://proxy.example.com',
+        proxy_req = ClientRequest('GET', URL('http://proxy.example.com'),
                                   auth=aiohttp.helpers.BasicAuth('user',
                                                                  'pass'),
                                   loop=self.loop)
         ClientRequestMock.return_value = proxy_req
 
-        proxy_resp = ClientResponse('get', 'http://proxy.example.com')
+        proxy_resp = ClientResponse('get', URL('http://proxy.example.com'))
         proxy_resp._loop = self.loop
         proxy_req.send = send_mock = mock.Mock()
         send_mock.return_value = proxy_resp
@@ -423,15 +427,15 @@ def test_https_auth(self, ClientRequestMock):
         self.assertNotIn('PROXY-AUTHORIZATION', proxy_req.headers)
 
         req = ClientRequest(
-            'GET', 'https://www.python.org',
-            proxy='http://proxy.example.com',
+            'GET', URL('https://www.python.org'),
+            proxy=URL('http://proxy.example.com'),
             loop=self.loop
         )
         self.assertNotIn('AUTHORIZATION', req.headers)
         self.assertNotIn('PROXY-AUTHORIZATION', req.headers)
         self.loop.run_until_complete(connector._create_connection(req))
 
-        self.assertEqual(req.path, '/')
+        self.assertEqual(req.url.path, '/')
         self.assertNotIn('AUTHORIZATION', req.headers)
         self.assertNotIn('PROXY-AUTHORIZATION', req.headers)
         self.assertNotIn('AUTHORIZATION', proxy_req.headers)
@@ -463,12 +467,12 @@ def tearDown(self):
 
     def test_ctor(self):
         connector = aiohttp.ProxyConnector(
-            'http://localhost:8118',
+            URL('http://localhost:8118'),
             proxy_auth=aiohttp.helpers.BasicAuth('user', 'pass'),
             loop=self.loop,
         )
 
-        self.assertEqual('http://localhost:8118', connector.proxy)
+        self.assertEqual('http://localhost:8118', str(connector.proxy))
         self.assertEqual(
             aiohttp.helpers.BasicAuth('user', 'pass'),
             connector.proxy_auth
@@ -477,10 +481,11 @@ def test_ctor(self):
 
     @mock.patch('aiohttp.connector.ClientRequest')
     def test_connect(self, ClientRequestMock):
-        req = ClientRequest('GET', 'http://www.python.org', loop=self.loop)
-        self.assertEqual(req.path, '/')
+        req = ClientRequest('GET', URL('http://www.python.org'),
+                            loop=self.loop)
+        self.assertEqual(req.url.path, '/')
 
-        connector = aiohttp.ProxyConnector('http://proxy.example.com',
+        connector = aiohttp.ProxyConnector(URL('http://proxy.example.com'),
                                            loop=self.loop)
         self.assertIs(self.loop, connector._loop)
 
@@ -489,7 +494,7 @@ def test_connect(self, ClientRequestMock):
         tr, proto = mock.Mock(), mock.Mock()
         self.loop.create_connection = make_mocked_coro((tr, proto))
         conn = self.loop.run_until_complete(connector.connect(req))
-        self.assertEqual(req.path, 'http://www.python.org/')
+        self.assertEqual(req.path, 'http://www.python.org')
         self.assertIs(conn._transport, tr)
         self.assertIs(conn._protocol, proto)
 
@@ -497,7 +502,7 @@ def test_connect(self, ClientRequestMock):
         tr.get_extra_info.assert_called_once_with('sslcontext')
 
         ClientRequestMock.assert_called_with(
-            'GET', 'http://proxy.example.com',
+            'GET', URL('http://proxy.example.com'),
             auth=None,
             headers={'Host': 'www.python.org'},
             loop=self.loop)
diff --git a/tests/test_wsgi.py b/tests/test_wsgi.py
index 5ebce0b4ade..9c86cb80aa1 100644
--- a/tests/test_wsgi.py
+++ b/tests/test_wsgi.py
@@ -7,6 +7,7 @@
 from unittest import mock
 
 import multidict
+
 import aiohttp
 from aiohttp import helpers, protocol, wsgi