diff --git a/aiohttp_jinja2/__init__.py b/aiohttp_jinja2/__init__.py
index c70c528c..1e5f39f0 100644
--- a/aiohttp_jinja2/__init__.py
+++ b/aiohttp_jinja2/__init__.py
@@ -1,6 +1,5 @@
 import asyncio
 import functools
-import sys
 import warnings
 from typing import (
     Any,
@@ -20,11 +19,12 @@
 import jinja2
 from aiohttp import web
 from aiohttp.abc import AbstractView
+from typing_extensions import Protocol
 
 from .helpers import GLOBAL_HELPERS
 from .typedefs import Filters
 
-__version__ = "1.3.0"
+__version__ = "1.4.0"
 
 __all__ = ("setup", "get_env", "render_template", "render_string", "template")
 
@@ -40,33 +40,25 @@
 _T = TypeVar("_T")
 _AbstractView = TypeVar("_AbstractView", bound=AbstractView)
 
-if sys.version_info >= (3, 8):
-    from typing import Protocol
-
-    class _TemplateWrapper(Protocol):
-        @overload
-        def __call__(
-            self, func: _SimpleTemplateHandler
-        ) -> Callable[[web.Request], Awaitable[web.StreamResponse]]:
-            ...
-
-        @overload
-        def __call__(
-            self, func: Callable[[_AbstractView], _TemplateReturnType]
-        ) -> Callable[[_AbstractView], Awaitable[web.StreamResponse]]:
-            ...
-
-        @overload
-        def __call__(
-            self, func: Callable[[_T, web.Request], _TemplateReturnType]
-        ) -> Callable[[_T, web.Request], Awaitable[web.StreamResponse]]:
-            ...
-
-
-else:
-    _TemplateHandler = Callable[..., _TemplateReturnType]
-    _WebHandler = Callable[..., Awaitable[web.StreamResponse]]
-    _TemplateWrapper = Callable[[_TemplateHandler], _WebHandler]
+
+class _TemplateWrapper(Protocol):
+    @overload
+    def __call__(
+        self, func: _SimpleTemplateHandler
+    ) -> Callable[[web.Request], Awaitable[web.StreamResponse]]:
+        ...
+
+    @overload
+    def __call__(
+        self, func: Callable[[_AbstractView], _TemplateReturnType]
+    ) -> Callable[[_AbstractView], Awaitable[web.StreamResponse]]:
+        ...
+
+    @overload
+    def __call__(
+        self, func: Callable[[_T, web.Request], _TemplateReturnType]
+    ) -> Callable[[_T, web.Request], Awaitable[web.StreamResponse]]:
+        ...
 
 
 def setup(
diff --git a/setup.py b/setup.py
index 9d39a2dc..f477edbf 100644
--- a/setup.py
+++ b/setup.py
@@ -29,7 +29,7 @@ def read(f):
     return open(os.path.join(os.path.dirname(__file__), f)).read().strip()
 
 
-install_requires = ["aiohttp>=3.6.3", "jinja2>=2.10.1"]
+install_requires = ["aiohttp>=3.6.3", "jinja2>=2.10.1", "typing_extensions>=3.7.4"]
 
 
 setup(