diff --git a/tempest/tests/cmd/test_run.py b/tempest/tests/cmd/test_run.py
index 0e00d94..8997a4c 100644
--- a/tempest/tests/cmd/test_run.py
+++ b/tempest/tests/cmd/test_run.py
@@ -49,7 +49,7 @@
         args = mock.Mock(spec=argparse.Namespace)
         setattr(args, 'smoke', False)
         setattr(args, 'regex', '')
-        self.assertIsNone(None, self.run_cmd._build_regex(args))
+        self.assertIsNone(self.run_cmd._build_regex(args))
 
     def test__build_regex_smoke(self):
         args = mock.Mock(spec=argparse.Namespace)