diff --git a/nova/tests/unit/test_test_utils.py b/nova/tests/unit/test_test_utils.py
index 8cc87fba6529..a06d362b93ef 100644
--- a/nova/tests/unit/test_test_utils.py
+++ b/nova/tests/unit/test_test_utils.py
@@ -66,5 +66,6 @@ class TestUtilsTestCase(test.TestCase):
                 self.assertTrue(test_utils.is_ipv6_supported())
 
             with fixtures.MonkeyPatch('sys.platform', 'linux2'):
-                with fixtures.MonkeyPatch('__builtin__.open', fake_open):
+                with fixtures.MonkeyPatch('six.moves.builtins.open',
+                                          fake_open):
                     self.assertFalse(test_utils.is_ipv6_supported())