diff --git a/lib/mongo_mapper/plugins/scopes.rb b/lib/mongo_mapper/plugins/scopes.rb
index 7af05e356..f0cc5f335 100644
--- a/lib/mongo_mapper/plugins/scopes.rb
+++ b/lib/mongo_mapper/plugins/scopes.rb
@@ -19,9 +19,9 @@ def scope(name, scope_options={})
         end
 
         def scopes
-          self._scopes || self._scopes = {}
+          self._scopes ||= {}
         end
       end
     end
   end
-end
\ No newline at end of file
+end