diff --git a/sphinx/__init__.py b/sphinx/__init__.py
index 86bcf88e5..9601d8e43 100644
--- a/sphinx/__init__.py
+++ b/sphinx/__init__.py
@@ -24,6 +24,7 @@ from .deprecation import RemovedInSphinx20Warning
 
 if False:
     # For type annotation
+    # note: Don't use typing.TYPE_CHECK here (for py27 and py34).
     from typing import Any  # NOQA
 
 
diff --git a/sphinx/apidoc.py b/sphinx/apidoc.py
index f397631fb..f6616e497 100644
--- a/sphinx/apidoc.py
+++ b/sphinx/apidoc.py
@@ -10,13 +10,12 @@
 """
 
 import warnings
+from typing import TYPE_CHECKING
 
 from sphinx.deprecation import RemovedInSphinx20Warning
 from sphinx.ext.apidoc import main as _main
 
-
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any  # NOQA
     from sphinx.application import Sphinx  # NOQA
 
diff --git a/sphinx/ext/autosectionlabel.py b/sphinx/ext/autosectionlabel.py
index 7a10b3e8d..80ca92711 100644
--- a/sphinx/ext/autosectionlabel.py
+++ b/sphinx/ext/autosectionlabel.py
@@ -16,8 +16,7 @@ from docutils import nodes
 from sphinx.util import logging
 from sphinx.util.nodes import clean_astext
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any, Dict  # NOQA
     from sphinx.application import Sphinx  # NOQA
 
diff --git a/sphinx/ext/extlinks.py b/sphinx/ext/extlinks.py
index 29bfe928f..53b051c45 100644
--- a/sphinx/ext/extlinks.py
+++ b/sphinx/ext/extlinks.py
@@ -24,14 +24,15 @@
     :license: BSD, see LICENSE for details.
 """
 
+from typing import TYPE_CHECKING
+
 from docutils import nodes, utils
 from six import iteritems
 
 import sphinx
 from sphinx.util.nodes import split_explicit_title
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any, Dict, List, Tuple  # NOQA
     from docutils.parsers.rst.states import Inliner  # NOQA
     from sphinx.application import Sphinx  # NOQA
diff --git a/sphinx/ext/githubpages.py b/sphinx/ext/githubpages.py
index bd7061fb7..f97c810f8 100644
--- a/sphinx/ext/githubpages.py
+++ b/sphinx/ext/githubpages.py
@@ -10,11 +10,11 @@
 """
 
 import os
+from typing import TYPE_CHECKING
 
 import sphinx
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any, Dict  # NOQA
     from sphinx.application import Sphinx  # NOQA
     from sphinx.environment import BuildEnvironment  # NOQA
diff --git a/sphinx/ext/jsmath.py b/sphinx/ext/jsmath.py
index b718162d2..e523b54c8 100644
--- a/sphinx/ext/jsmath.py
+++ b/sphinx/ext/jsmath.py
@@ -10,6 +10,8 @@
     :license: BSD, see LICENSE for details.
 """
 
+from typing import TYPE_CHECKING
+
 from docutils import nodes
 
 import sphinx
@@ -19,8 +21,7 @@ from sphinx.ext.mathbase import setup_math as mathbase_setup
 from sphinx.locale import _
 
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any, Dict  # NOQA
     from sphinx.application import Sphinx  # NOQA
 
diff --git a/sphinx/ext/mathjax.py b/sphinx/ext/mathjax.py
index 4ebfd35ed..9f8013b2b 100644
--- a/sphinx/ext/mathjax.py
+++ b/sphinx/ext/mathjax.py
@@ -11,6 +11,8 @@
     :license: BSD, see LICENSE for details.
 """
 
+from typing import TYPE_CHECKING
+
 from docutils import nodes
 
 import sphinx
@@ -19,9 +21,7 @@ from sphinx.ext.mathbase import get_node_equation_number
 from sphinx.ext.mathbase import setup_math as mathbase_setup
 from sphinx.locale import _
 
-
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any, Dict  # NOQA
     from sphinx.application import Sphinx  # NOQA
 
diff --git a/sphinx/quickstart.py b/sphinx/quickstart.py
index 8cad0640b..dbdfb47c1 100644
--- a/sphinx/quickstart.py
+++ b/sphinx/quickstart.py
@@ -10,12 +10,12 @@
 """
 
 import warnings
+from typing import TYPE_CHECKING
 
 from sphinx.cmd.quickstart import main as _main
 from sphinx.deprecation import RemovedInSphinx20Warning
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any  # NOQA
 
 
diff --git a/sphinx/search/da.py b/sphinx/search/da.py
index aac6c4130..186219cca 100644
--- a/sphinx/search/da.py
+++ b/sphinx/search/da.py
@@ -15,8 +15,7 @@ from sphinx.search import SearchLanguage, parse_stop_word
 
 import snowballstemmer
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any  # NOQA
 
 
diff --git a/sphinx/search/de.py b/sphinx/search/de.py
index 87c4cf617..186e4ab08 100644
--- a/sphinx/search/de.py
+++ b/sphinx/search/de.py
@@ -15,8 +15,7 @@ from sphinx.search import SearchLanguage, parse_stop_word
 
 import snowballstemmer
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any  # NOQA
 
 
diff --git a/sphinx/search/es.py b/sphinx/search/es.py
index 972ec1495..48783feff 100644
--- a/sphinx/search/es.py
+++ b/sphinx/search/es.py
@@ -15,8 +15,7 @@ from sphinx.search import SearchLanguage, parse_stop_word
 
 import snowballstemmer
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any  # NOQA
 
 
diff --git a/sphinx/search/fi.py b/sphinx/search/fi.py
index b089bef3a..039035bd6 100644
--- a/sphinx/search/fi.py
+++ b/sphinx/search/fi.py
@@ -15,8 +15,7 @@ from sphinx.search import SearchLanguage, parse_stop_word
 
 import snowballstemmer
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any  # NOQA
 
 
diff --git a/sphinx/search/fr.py b/sphinx/search/fr.py
index 0f2b68a69..0c42843ec 100644
--- a/sphinx/search/fr.py
+++ b/sphinx/search/fr.py
@@ -15,8 +15,7 @@ from sphinx.search import SearchLanguage, parse_stop_word
 
 import snowballstemmer
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any  # NOQA
 
 
diff --git a/sphinx/search/hu.py b/sphinx/search/hu.py
index d3bcf2974..c2abbd677 100644
--- a/sphinx/search/hu.py
+++ b/sphinx/search/hu.py
@@ -15,8 +15,7 @@ from sphinx.search import SearchLanguage, parse_stop_word
 
 import snowballstemmer
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any  # NOQA
 
 
diff --git a/sphinx/search/it.py b/sphinx/search/it.py
index 64d7c7538..1a26c4488 100644
--- a/sphinx/search/it.py
+++ b/sphinx/search/it.py
@@ -15,8 +15,7 @@ from sphinx.search import SearchLanguage, parse_stop_word
 
 import snowballstemmer
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any  # NOQA
 
 
diff --git a/sphinx/search/nl.py b/sphinx/search/nl.py
index 32fb86937..fc26bbd2f 100644
--- a/sphinx/search/nl.py
+++ b/sphinx/search/nl.py
@@ -15,8 +15,7 @@ from sphinx.search import SearchLanguage, parse_stop_word
 
 import snowballstemmer
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any  # NOQA
 
 
diff --git a/sphinx/search/no.py b/sphinx/search/no.py
index d1f849228..d582cd02c 100644
--- a/sphinx/search/no.py
+++ b/sphinx/search/no.py
@@ -15,8 +15,7 @@ from sphinx.search import SearchLanguage, parse_stop_word
 
 import snowballstemmer
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any  # NOQA
 
 
diff --git a/sphinx/search/pt.py b/sphinx/search/pt.py
index dc43c0330..1fd0b65c8 100644
--- a/sphinx/search/pt.py
+++ b/sphinx/search/pt.py
@@ -15,8 +15,7 @@ from sphinx.search import SearchLanguage, parse_stop_word
 
 import snowballstemmer
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any  # NOQA
 
 
diff --git a/sphinx/search/ru.py b/sphinx/search/ru.py
index 75870b08f..085569f20 100644
--- a/sphinx/search/ru.py
+++ b/sphinx/search/ru.py
@@ -15,8 +15,7 @@ from sphinx.search import SearchLanguage, parse_stop_word
 
 import snowballstemmer
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any  # NOQA
 
 
diff --git a/sphinx/search/sv.py b/sphinx/search/sv.py
index 555b4b641..f6d40feed 100644
--- a/sphinx/search/sv.py
+++ b/sphinx/search/sv.py
@@ -15,8 +15,7 @@ from sphinx.search import SearchLanguage, parse_stop_word
 
 import snowballstemmer
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any
 
 swedish_stopwords = parse_stop_word(u'''
diff --git a/sphinx/testing/path.py b/sphinx/testing/path.py
index 209046246..5f59ad30b 100644
--- a/sphinx/testing/path.py
+++ b/sphinx/testing/path.py
@@ -10,11 +10,11 @@ import os
 import shutil
 import sys
 from io import open
+from typing import TYPE_CHECKING
 
 from six import PY2, text_type
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any, Callable, IO, List  # NOQA