diff --git a/neutron/manager.py b/neutron/manager.py
index 2c4e7f9945..a84056d2f3 100644
--- a/neutron/manager.py
+++ b/neutron/manager.py
@@ -176,7 +176,7 @@ class NeutronManager(object):
             # for the same type is a fatal exception
             if plugin_inst.get_plugin_type() in self.service_plugins:
                 raise ValueError(_("Multiple plugins for service "
-                                   "%s were configured"),
+                                   "%s were configured") %
                                  plugin_inst.get_plugin_type())
 
             self.service_plugins[plugin_inst.get_plugin_type()] = plugin_inst
diff --git a/neutron/tests/unit/test_neutron_manager.py b/neutron/tests/unit/test_neutron_manager.py
index 4a8eb0e6dc..3017f660e8 100644
--- a/neutron/tests/unit/test_neutron_manager.py
+++ b/neutron/tests/unit/test_neutron_manager.py
@@ -81,7 +81,8 @@ class NeutronManagerTestCase(base.BaseTestCase):
                                "neutron.tests.unit.dummy_plugin."
                                "DummyServicePlugin"])
         cfg.CONF.set_override("core_plugin", DB_PLUGIN_KLASS)
-        self.assertRaises(ValueError, manager.NeutronManager.get_instance)
+        e = self.assertRaises(ValueError, manager.NeutronManager.get_instance)
+        self.assertIn(constants.DUMMY, e.message)
 
     def test_multiple_plugins_by_name_specified_for_service_type(self):
         cfg.CONF.set_override("service_plugins", ["dummy", "dummy"])
@@ -102,7 +103,8 @@ class NeutronManagerTestCase(base.BaseTestCase):
         cfg.CONF.set_override("core_plugin",
                               "neutron.tests.unit.test_neutron_manager."
                               "MultiServiceCorePlugin")
-        self.assertRaises(ValueError, manager.NeutronManager.get_instance)
+        e = self.assertRaises(ValueError, manager.NeutronManager.get_instance)
+        self.assertIn(constants.DUMMY, e.message)
 
     def test_core_plugin_supports_services(self):
         cfg.CONF.set_override("core_plugin",