diff --git a/backbone/backbone.d.ts b/backbone/backbone.d.ts
index aad4cffde..32205e1f9 100644
--- a/backbone/backbone.d.ts
+++ b/backbone/backbone.d.ts
@@ -80,7 +80,7 @@ declare module Backbone {
     }
 
     class ModelBase extends Events {
-        url: any;
+        url(): any;
         parse(response: any, options?: any): any;
         toJSON(options?: any): any;
         sync(...arg: any[]): JQueryXHR;