diff --git a/glanceclient/tests/unit/v2/test_shell_v2.py b/glanceclient/tests/unit/v2/test_shell_v2.py
index faaad01f..5967b004 100644
--- a/glanceclient/tests/unit/v2/test_shell_v2.py
+++ b/glanceclient/tests/unit/v2/test_shell_v2.py
@@ -833,7 +833,7 @@ class ShellV2Test(testtools.TestCase):
 
             test_shell.do_md_resource_type_list(self.gc, args)
 
-            mocked_list.assert_called_once()
+            self.assertEqual(1, mocked_list.call_count)
 
     def test_do_md_namespace_resource_type_list(self):
         args = self._make_args({'namespace': 'MyNamespace'})
diff --git a/test-requirements.txt b/test-requirements.txt
index 2ef5e9ac..ebf9fc06 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -5,7 +5,8 @@ hacking<0.11,>=0.10.0
 
 coverage>=3.6
 discover
-mock>=1.0
+mock>=1.0;python_version!='2.6'
+mock==1.0.1;python_version=='2.6'
 oslosphinx>=2.5.0 # Apache-2.0
 sphinx!=1.2.0,!=1.3b1,<1.3,>=1.1.2
 testrepository>=0.0.18