diff --git a/lms/envs/devstack.py b/lms/envs/devstack.py
index 3d5762d47a..10cff1c70d 100644
--- a/lms/envs/devstack.py
+++ b/lms/envs/devstack.py
@@ -45,11 +45,9 @@ ANALYTICS_DASHBOARD_URL = None
 ################################ DEBUG TOOLBAR ################################
 
 INSTALLED_APPS += ('debug_toolbar', 'debug_toolbar_mongo')
-MIDDLEWARE_CLASSES = (
-    (
-        'django_comment_client.utils.QueryCountDebugMiddleware',
-        'debug_toolbar.middleware.DebugToolbarMiddleware',
-    ) + MIDDLEWARE_CLASSES
+MIDDLEWARE_CLASSES += (
+    'django_comment_client.utils.QueryCountDebugMiddleware',
+    'debug_toolbar.middleware.DebugToolbarMiddleware',
 )
 INTERNAL_IPS = ('127.0.0.1',)