diff --git a/tests/unit/test_http.py b/tests/unit/test_http.py
index d743774596b4..ea72c3a18691 100644
--- a/tests/unit/test_http.py
+++ b/tests/unit/test_http.py
@@ -71,6 +71,41 @@ def _test_factory(fifo, start):
         assert len(set(id(obj) for obj in objects)) == len(threads)
 
 
+class TestUnicodeRedirectTween:
+    def test_basic_redirect(self):
+        response = pretend.stub(location="/a/path/to/nowhere")
+        handler = pretend.call_recorder(lambda request: response)
+        registry = pretend.stub()
+        tween = warehouse.http.unicode_redirect_tween_factory(
+            handler, registry)
+        request = pretend.stub(
+            path="/A/pAtH/tO/nOwHeRe/",
+        )
+        assert tween(request) == response
+
+    def test_unicode_basic_redirect(self):
+        response = pretend.stub(location="/pypi/\u2603/json/")
+        handler = pretend.call_recorder(lambda request: response)
+        registry = pretend.stub()
+        tween = warehouse.http.unicode_redirect_tween_factory(
+            handler, registry)
+        request = pretend.stub(
+            path="/pypi/snowman/json/",
+        )
+        assert tween(request).location == "/pypi/%E2%98%83/json/"
+
+    def test_not_redirect(self):
+        response = pretend.stub(location=None)
+        handler = pretend.call_recorder(lambda request: response)
+        registry = pretend.stub()
+        tween = warehouse.http.unicode_redirect_tween_factory(
+            handler, registry)
+        request = pretend.stub(
+            path="/wu/tang/",
+        )
+        assert tween(request) == response
+
+
 def test_includeme():
     config = pretend.stub(
         registry=pretend.stub(
@@ -79,10 +114,17 @@ def test_includeme():
         add_request_method=pretend.call_recorder(
             lambda *args, **kwargs: None
         ),
+        add_tween=pretend.call_recorder(
+            lambda *args, **kwargs: None
+        ),
     )
     warehouse.http.includeme(config)
 
     assert len(config.add_request_method.calls) == 1
+    assert len(config.add_tween.calls) == 1
     call = config.add_request_method.calls[0]
     assert isinstance(call.args[0], warehouse.http.ThreadLocalSessionFactory)
     assert call.kwargs == {"name": "http", "reify": True}
+    assert config.add_tween.calls == [
+        pretend.call("warehouse.http.unicode_redirect_tween_factory")
+    ]
diff --git a/warehouse/http.py b/warehouse/http.py
index 8da234f5867f..c1bca4c1680c 100644
--- a/warehouse/http.py
+++ b/warehouse/http.py
@@ -13,6 +13,8 @@
 import threading
 import requests
 
+from urllib.parse import quote_plus
+
 
 class ThreadLocalSessionFactory:
     def __init__(self, config=None):
@@ -37,8 +39,25 @@ def __call__(self, request):
             return session
 
 
+def unicode_redirect_tween_factory(handler, request):
+
+    def unicode_redirect_tween(request):
+        response = handler(request)
+        if response.location:
+            try:
+                response.location.encode('ascii')
+            except UnicodeEncodeError:
+                response.location = '/'.join(
+                    [quote_plus(x) for x in response.location.split('/')])
+
+        return response
+
+    return unicode_redirect_tween
+
+
 def includeme(config):
     config.add_request_method(
         ThreadLocalSessionFactory(config.registry.settings.get("http")),
         name="http", reify=True
     )
+    config.add_tween("warehouse.http.unicode_redirect_tween_factory")