diff --git a/jquery/jquery-1.8.d.ts b/jquery/jquery-1.8.d.ts
index 76e14c58b..2872acc05 100644
--- a/jquery/jquery-1.8.d.ts
+++ b/jquery/jquery-1.8.d.ts
@@ -179,7 +179,8 @@ interface JQueryStatic {
 
     ajaxSettings: JQueryAjaxSettings;
 
-    ajaxSetup(options?: any);
+    ajaxSetup();
+    ajaxSetup(options: JQueryAjaxSettings);
 
     get(url: string, data?: any, success?: any, dataType?: any): JQueryXHR;
     getJSON(url: string, data?: any, success?: any): JQueryXHR;