diff --git a/.coveragerc b/.coveragerc
index ed1fb97596..fc2321e877 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -24,3 +24,5 @@ exclude_lines =
     \#\s*pragma: no cover
     ^\s*raise NotImplementedError\b
     ^\s*return NotImplemented\b
+
+    ^\s*if TYPE_CHECKING:
diff --git a/changelog/6435.trivial.rst b/changelog/6435.trivial.rst
new file mode 100644
index 0000000000..78a4a3bac8
--- /dev/null
+++ b/changelog/6435.trivial.rst
@@ -0,0 +1 @@
+Added ``typing_extensions`` as dependency on Python 3.5.1 or lower.
diff --git a/doc/en/conf.py b/doc/en/conf.py
index 3fb6002bc1..bd2fd9871f 100644
--- a/doc/en/conf.py
+++ b/doc/en/conf.py
@@ -19,8 +19,9 @@
 import sys
 
 from _pytest import __version__ as version
+from _pytest.compat import TYPE_CHECKING
 
-if False:  # TYPE_CHECKING
+if TYPE_CHECKING:
     import sphinx.application
 
 
diff --git a/src/_pytest/_code/code.py b/src/_pytest/_code/code.py
index d1a8ec2f1e..f0e503f4f1 100644
--- a/src/_pytest/_code/code.py
+++ b/src/_pytest/_code/code.py
@@ -32,8 +32,9 @@
 from _pytest._io.saferepr import safeformat
 from _pytest._io.saferepr import saferepr
 from _pytest.compat import overload
+from _pytest.compat import TYPE_CHECKING
 
-if False:  # TYPE_CHECKING
+if TYPE_CHECKING:
     from typing import Type
     from typing_extensions import Literal
     from weakref import ReferenceType  # noqa: F401
diff --git a/src/_pytest/compat.py b/src/_pytest/compat.py
index 9eec0aedaa..117554c448 100644
--- a/src/_pytest/compat.py
+++ b/src/_pytest/compat.py
@@ -1,12 +1,18 @@
 """
 python version compatibility code
 """
+import sys  # isort:skip
+
+if sys.version_info < (3, 5, 2):
+    TYPE_CHECKING = False  # type: bool
+else:
+    from typing import TYPE_CHECKING
+
 import functools
 import inspect
 import io
 import os
 import re
-import sys
 from contextlib import contextmanager
 from inspect import Parameter
 from inspect import signature
@@ -28,7 +34,8 @@
 from _pytest.outcomes import fail
 from _pytest.outcomes import TEST_OUTCOME
 
-if False:  # TYPE_CHECKING
+
+if TYPE_CHECKING:
     from typing import Type  # noqa: F401 (used in type string)
 
 
diff --git a/src/_pytest/config/__init__.py b/src/_pytest/config/__init__.py
index fb965b2615..d6a704b1d8 100644
--- a/src/_pytest/config/__init__.py
+++ b/src/_pytest/config/__init__.py
@@ -37,12 +37,13 @@
 from _pytest._code import ExceptionInfo
 from _pytest._code import filter_traceback
 from _pytest.compat import importlib_metadata
+from _pytest.compat import TYPE_CHECKING
 from _pytest.outcomes import fail
 from _pytest.outcomes import Skipped
 from _pytest.pathlib import Path
 from _pytest.warning_types import PytestConfigWarning
 
-if False:  # TYPE_CHECKING
+if TYPE_CHECKING:
     from typing import Type
 
     from .argparsing import Argument
diff --git a/src/_pytest/config/argparsing.py b/src/_pytest/config/argparsing.py
index d0870ed56a..fa9d8f5dc6 100644
--- a/src/_pytest/config/argparsing.py
+++ b/src/_pytest/config/argparsing.py
@@ -15,9 +15,10 @@
 
 import py
 
+from _pytest.compat import TYPE_CHECKING
 from _pytest.config.exceptions import UsageError
 
-if False:  # TYPE_CHECKING
+if TYPE_CHECKING:
     from typing import NoReturn
     from typing_extensions import Literal  # noqa: F401
 
diff --git a/src/_pytest/config/findpaths.py b/src/_pytest/config/findpaths.py
index 728246dfcc..d9b5f7543f 100644
--- a/src/_pytest/config/findpaths.py
+++ b/src/_pytest/config/findpaths.py
@@ -5,9 +5,10 @@
 import py
 
 from .exceptions import UsageError
+from _pytest.compat import TYPE_CHECKING
 from _pytest.outcomes import fail
 
-if False:
+if TYPE_CHECKING:
     from . import Config  # noqa: F401
 
 
diff --git a/src/_pytest/doctest.py b/src/_pytest/doctest.py
index 3475ac9c2b..30eaba0353 100644
--- a/src/_pytest/doctest.py
+++ b/src/_pytest/doctest.py
@@ -19,12 +19,13 @@
 from _pytest._code.code import ReprFileLocation
 from _pytest._code.code import TerminalRepr
 from _pytest.compat import safe_getattr
+from _pytest.compat import TYPE_CHECKING
 from _pytest.fixtures import FixtureRequest
 from _pytest.outcomes import Skipped
 from _pytest.python_api import approx
 from _pytest.warning_types import PytestWarning
 
-if False:  # TYPE_CHECKING
+if TYPE_CHECKING:
     import doctest
     from typing import Type
 
diff --git a/src/_pytest/fixtures.py b/src/_pytest/fixtures.py
index 44802e0009..fe5410c39d 100644
--- a/src/_pytest/fixtures.py
+++ b/src/_pytest/fixtures.py
@@ -27,12 +27,13 @@
 from _pytest.compat import is_generator
 from _pytest.compat import NOTSET
 from _pytest.compat import safe_getattr
+from _pytest.compat import TYPE_CHECKING
 from _pytest.deprecated import FIXTURE_POSITIONAL_ARGUMENTS
 from _pytest.deprecated import FUNCARGNAMES
 from _pytest.outcomes import fail
 from _pytest.outcomes import TEST_OUTCOME
 
-if False:  # TYPE_CHECKING
+if TYPE_CHECKING:
     from typing import Type
 
     from _pytest import nodes
diff --git a/src/_pytest/nodes.py b/src/_pytest/nodes.py
index 3eaafa91d5..13707c89a5 100644
--- a/src/_pytest/nodes.py
+++ b/src/_pytest/nodes.py
@@ -17,6 +17,7 @@
 from _pytest._code.code import ReprExceptionInfo
 from _pytest.compat import cached_property
 from _pytest.compat import getfslineno
+from _pytest.compat import TYPE_CHECKING
 from _pytest.config import Config
 from _pytest.deprecated import NODE_USE_FROM_PARENT
 from _pytest.fixtures import FixtureDef
@@ -27,7 +28,7 @@
 from _pytest.mark.structures import NodeKeywords
 from _pytest.outcomes import Failed
 
-if False:  # TYPE_CHECKING
+if TYPE_CHECKING:
     # Imported here due to circular import.
     from _pytest.main import Session  # noqa: F401
 
diff --git a/src/_pytest/outcomes.py b/src/_pytest/outcomes.py
index 9471366257..6ac97af613 100644
--- a/src/_pytest/outcomes.py
+++ b/src/_pytest/outcomes.py
@@ -8,7 +8,9 @@
 
 from packaging.version import Version
 
-if False:  # TYPE_CHECKING
+from _pytest.compat import TYPE_CHECKING
+
+if TYPE_CHECKING:
     from typing import NoReturn
 
 
diff --git a/src/_pytest/pytester.py b/src/_pytest/pytester.py
index d2313f2808..9c60dc1aaf 100644
--- a/src/_pytest/pytester.py
+++ b/src/_pytest/pytester.py
@@ -28,6 +28,7 @@
 from _pytest._io.saferepr import saferepr
 from _pytest.capture import MultiCapture
 from _pytest.capture import SysCapture
+from _pytest.compat import TYPE_CHECKING
 from _pytest.fixtures import FixtureRequest
 from _pytest.main import ExitCode
 from _pytest.main import Session
@@ -35,7 +36,7 @@
 from _pytest.pathlib import Path
 from _pytest.reports import TestReport
 
-if False:  # TYPE_CHECKING
+if TYPE_CHECKING:
     from typing import Type
 
 
@@ -189,7 +190,7 @@ def __repr__(self):
         del d["_name"]
         return "<ParsedCall {!r}(**{!r})>".format(self._name, d)
 
-    if False:  # TYPE_CHECKING
+    if TYPE_CHECKING:
         # The class has undetermined attributes, this tells mypy about it.
         def __getattr__(self, key):
             raise NotImplementedError()
diff --git a/src/_pytest/python_api.py b/src/_pytest/python_api.py
index 9f206ce9b4..5e5eddc5b0 100644
--- a/src/_pytest/python_api.py
+++ b/src/_pytest/python_api.py
@@ -23,9 +23,10 @@
 import _pytest._code
 from _pytest.compat import overload
 from _pytest.compat import STRING_TYPES
+from _pytest.compat import TYPE_CHECKING
 from _pytest.outcomes import fail
 
-if False:  # TYPE_CHECKING
+if TYPE_CHECKING:
     from typing import Type  # noqa: F401 (used in type string)
 
 
diff --git a/src/_pytest/recwarn.py b/src/_pytest/recwarn.py
index 5cf32c8940..956a907831 100644
--- a/src/_pytest/recwarn.py
+++ b/src/_pytest/recwarn.py
@@ -12,10 +12,11 @@
 from typing import Union
 
 from _pytest.compat import overload
+from _pytest.compat import TYPE_CHECKING
 from _pytest.fixtures import yield_fixture
 from _pytest.outcomes import fail
 
-if False:  # TYPE_CHECKING
+if TYPE_CHECKING:
     from typing import Type
 
 
diff --git a/src/_pytest/runner.py b/src/_pytest/runner.py
index 50e4d4307a..417783b47e 100644
--- a/src/_pytest/runner.py
+++ b/src/_pytest/runner.py
@@ -15,12 +15,13 @@
 from .reports import CollectReport
 from .reports import TestReport
 from _pytest._code.code import ExceptionInfo
+from _pytest.compat import TYPE_CHECKING
 from _pytest.nodes import Node
 from _pytest.outcomes import Exit
 from _pytest.outcomes import Skipped
 from _pytest.outcomes import TEST_OUTCOME
 
-if False:  # TYPE_CHECKING
+if TYPE_CHECKING:
     from typing import Type
 
 #
diff --git a/src/_pytest/warning_types.py b/src/_pytest/warning_types.py
index 22cb17dbae..2e03c578c0 100644
--- a/src/_pytest/warning_types.py
+++ b/src/_pytest/warning_types.py
@@ -4,8 +4,9 @@
 
 import attr
 
+from _pytest.compat import TYPE_CHECKING
 
-if False:  # TYPE_CHECKING
+if TYPE_CHECKING:
     from typing import Type  # noqa: F401 (used in type string)
 
 
diff --git a/tox.ini b/tox.ini
index c26b7cf828..9415edc6a1 100644
--- a/tox.ini
+++ b/tox.ini
@@ -182,6 +182,8 @@ markers =
 [flake8]
 max-line-length = 120
 extend-ignore = E203
+per-file-ignores =
+  src/_pytest/compat.py: E402
 
 [isort]
 ; This config mimics what reorder-python-imports does.