diff --git a/python/helpers/tests/generator3_tests/tox.ini b/python/helpers/tests/generator3_tests/tox.ini
index f59f77bffeb9..5c2b8418b45b 100644
--- a/python/helpers/tests/generator3_tests/tox.ini
+++ b/python/helpers/tests/generator3_tests/tox.ini
@@ -6,4 +6,4 @@ envlist = py27,py35,py36,py37
 setenv =
     PYTHONPATH = {toxinidir}/..{:}{toxinidir}/../..
 commands =
-    python -m unittest discover
\ No newline at end of file
+    python -m unittest {posargs:discover}
\ No newline at end of file