diff --git a/tox.ini b/tox.ini
index 30c0bb38d..b9610cd04 100644
--- a/tox.ini
+++ b/tox.ini
@@ -39,7 +39,6 @@ setenv = TESTS_DIR=./ironicclient/tests/functional
 
 [flake8]
 ignore =
-builtins = _
 exclude = .venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,build,tools
 
 [hacking]