diff --git a/nova/tests/uuidsentinel.py b/nova/tests/uuidsentinel.py
index 5011d7a8f..5fb7abe43 100644
--- a/nova/tests/uuidsentinel.py
+++ b/nova/tests/uuidsentinel.py
@@ -23,7 +23,7 @@ class UUIDSentinels(object):
         if name.startswith('_'):
             raise ValueError('Sentinels must not start with _')
         if name not in self._sentinels:
-            self._sentinels[name] = str(self._uuid_module.generate_uuid())
+            self._sentinels[name] = self._uuid_module.generate_uuid()
         return self._sentinels[name]