diff --git a/tox.ini b/tox.ini
index f02792f9..09eb3646 100644
--- a/tox.ini
+++ b/tox.ini
@@ -25,4 +25,3 @@ commands = python setup.py build_sphinx
 [flake8]
 show-source = True
 exclude = .tox,dist,doc,*.egg,build
-builtins = _