Use typing.TYPE_CHECKING for typehints

1 files changed, 2 insertions, 2 deletions

diff --git a/sphinx/ext/pngmath.py b/sphinx/ext/pngmath.py
index ebb05e615..96a3f02f4 100644
--- a/sphinx/ext/pngmath.py
+++ b/sphinx/ext/pngmath.py
@@ -18,6 +18,7 @@ import tempfile
 from hashlib import sha1
 from os import path
 from subprocess import Popen, PIPE
+from typing import TYPE_CHECKING
 
 from docutils import nodes
 from six import text_type
@@ -31,8 +32,7 @@ from sphinx.util.osutil import ensuredir, ENOENT, cd
 from sphinx.util.png import read_png_depth, write_png_depth
 from sphinx.util.pycompat import sys_encoding
 
-if False:
-    # For type annotation
+if TYPE_CHECKING:
     from typing import Any, Dict, Tuple  # NOQA
     from sphinx.application import Sphinx  # NOQA
     from sphinx.ext.mathbase import math as math_node, displaymath  # NOQA