diff --git a/restangular/restangular.d.ts b/restangular/restangular.d.ts
index b1a975ccfc..8daa5c0b08 100644
--- a/restangular/restangular.d.ts
+++ b/restangular/restangular.d.ts
@@ -93,6 +93,7 @@ declare namespace restangular {
     service(route: string, parent?: any): IService;
     stripRestangular(element: any): any;
     extendModel(route: string, extender: (model: IElement) => any): void;
+    extendCollection(route: string, extender: (collection: ICollection) => any): void;
   }
 
   interface IElement extends IService {