diff --git a/Definitions/jquery-1.8.d.ts b/Definitions/jquery-1.8.d.ts
index 07b193276..8aa46adc8 100644
--- a/Definitions/jquery-1.8.d.ts
+++ b/Definitions/jquery-1.8.d.ts
@@ -58,7 +58,7 @@ interface JQueryAjaxSettings {
     Interface for the jqXHR object
 */
 interface JQueryXHR extends XMLHttpRequest, JQueryPromise {
-    overrideMimeType();
+    overrideMimeType(mimeType: string);
 }
 
 /*