diff --git a/flask_mongoengine/__init__.py b/flask_mongoengine/__init__.py
index 47683937..3ea7ef4a 100644
--- a/flask_mongoengine/__init__.py
+++ b/flask_mongoengine/__init__.py
@@ -94,8 +94,8 @@ def init_app(self, app, config=None):
 
         # Store objects in application instance so that multiple apps do
         # not end up accessing the same objects.
-        app.extensions['mongoengine'] = {self: {'app': app,
-                                                'conn': connection}}
+        app.extensions['mongoengine'][self] = {'app': app,
+                                               'conn': connection}
 
     @property
     def connection(self):