diff --git a/winjs/winjs.d.ts b/winjs/winjs.d.ts
index b5ded7a59..2b8e95c35 100644
--- a/winjs/winjs.d.ts
+++ b/winjs/winjs.d.ts
@@ -64,7 +64,7 @@ interface IOHelper {
 	 * @param text The content to be written to the file.
 	 * @returns A promise that completes with a value that is the number of characters written.
 	 **/
-	writeText(fileName: string, text: string): WinJS.Promise<void>;
+	writeText(fileName: string, text: string): WinJS.Promise<number>;
 }
 
 /**