diff --git a/nova/tests/functional/test_middleware.py b/nova/tests/functional/test_middleware.py
index 3a4d8d64ef..ca225409bd 100644
--- a/nova/tests/functional/test_middleware.py
+++ b/nova/tests/functional/test_middleware.py
@@ -36,7 +36,7 @@ class TestCORSMiddleware(api_sample_base.ApiSampleTestBaseV21):
         def _mock_getattr(instance, key):
             if key != 'allowed_origin':
                 return self._original_call_method(instance, key)
-            return "http://valid.example.com"
+            return ["http://valid.example.com"]
 
         self._original_call_method = cfg.ConfigOpts.GroupAttr.__getattr__
         cfg.ConfigOpts.GroupAttr.__getattr__ = _mock_getattr