diff --git a/ckan/plugins/core.py b/ckan/plugins/core.py
index 283538dec3c..9a95a42590e 100644
--- a/ckan/plugins/core.py
+++ b/ckan/plugins/core.py
@@ -114,7 +114,7 @@ def plugins_update():
     # check and disable any that should not be active.
     for env in PluginGlobals.env.values():
         for service, id_ in env.singleton_services.items():
-            if service.__class__ not in _PLUGINS_CLASS:
+            if service not in _PLUGINS_CLASS:
                 PluginGlobals.plugin_instances[id_].deactivate()
 
     # Reset CKAN to reflect the currently enabled extensions.