diff --git a/tests/operators/test_virtualenv_operator.py b/tests/operators/test_virtualenv_operator.py
index b1d62e3452648..65c6030196318 100644
--- a/tests/operators/test_virtualenv_operator.py
+++ b/tests/operators/test_virtualenv_operator.py
@@ -163,6 +163,7 @@ def f(a):
 
     def test_string_args(self):
         def f():
+            global virtualenv_string_args
             print(virtualenv_string_args)
             if virtualenv_string_args[0] != virtualenv_string_args[2]:
                 raise Exception