diff --git a/os_vif/__init__.py b/os_vif/__init__.py
index 968cfcc..2dac738 100644
--- a/os_vif/__init__.py
+++ b/os_vif/__init__.py
@@ -37,7 +37,7 @@ def initialize(reset=False):
     if reset or (_EXT_MANAGER is None):
         _EXT_MANAGER = extension.ExtensionManager(namespace='os_vif',
                                                   invoke_on_load=False)
-        for plugin_name in _EXT_MANAGER.keys():
+        for plugin_name in _EXT_MANAGER.names():
             cls = _EXT_MANAGER[plugin_name].plugin
             obj = cls.load(plugin_name)
             _EXT_MANAGER[plugin_name].obj = obj
diff --git a/os_vif/tests/test_os_vif.py b/os_vif/tests/test_os_vif.py
index ce0f3e2..dcf6ce3 100644
--- a/os_vif/tests/test_os_vif.py
+++ b/os_vif/tests/test_os_vif.py
@@ -103,8 +103,10 @@ class TestOSVIF(base.TestCase):
                                   entry_point="os-vif",
                                   plugin=DemoPlugin,
                                   obj=None)
-        with mock.patch('stevedore.extension.ExtensionManager',
-                        return_value={'foobar': plg}):
+        with mock.patch('stevedore.extension.ExtensionManager.names',
+                        return_value=['foobar']),\
+                mock.patch('stevedore.extension.ExtensionManager.__getitem__',
+                           return_value=plg):
             os_vif.initialize()
             info = objects.instance_info.InstanceInfo()
             vif = objects.vif.VIFBridge(id='uniq',
@@ -118,8 +120,10 @@ class TestOSVIF(base.TestCase):
                                   entry_point="os-vif",
                                   plugin=DemoPlugin,
                                   obj=None)
-        with mock.patch('stevedore.extension.ExtensionManager',
-                        return_value={'foobar': plg}):
+        with mock.patch('stevedore.extension.ExtensionManager.names',
+                        return_value=['foobar']),\
+                mock.patch('stevedore.extension.ExtensionManager.__getitem__',
+                           return_value=plg):
             os_vif.initialize()
             info = objects.instance_info.InstanceInfo()
             vif = objects.vif.VIFBridge(id='uniq',