diff --git a/tox.ini b/tox.ini
index db4f00f2..d4db4dc0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -41,8 +41,7 @@ commands =
 
 [testenv:pycodestyle]
 commands =
-  pycodestyle gunicorn \
-  --exclude=gunicorn/six.py
+  pycodestyle gunicorn
 deps =
   pycodestyle