diff --git a/tests/functional/test_install.py b/tests/functional/test_install.py
index 374c2403af7..a8d3cf9628e 100644
--- a/tests/functional/test_install.py
+++ b/tests/functional/test_install.py
@@ -5,6 +5,7 @@
 import textwrap
 from os.path import curdir, join, pardir
 
+# Ignore because flake8 can't detect the use inside skipif().
 import pip._vendor.six  # noqa: F401
 import pytest