diff --git a/keystoneclient/tests/unit/utils.py b/keystoneclient/tests/unit/utils.py
index b3405fbc..1b45c36b 100644
--- a/keystoneclient/tests/unit/utils.py
+++ b/keystoneclient/tests/unit/utils.py
@@ -179,7 +179,7 @@ class DisableModuleFixture(fixtures.Fixture):
 
     def clear_module(self):
         cleared_modules = {}
-        for fullname in sys.modules.keys():
+        for fullname in list(sys.modules):
             if (fullname == self.module or
                     fullname.startswith(self.module + '.')):
                 cleared_modules[fullname] = sys.modules.pop(fullname)