diff --git a/jqueryui/jqueryui.d.ts b/jqueryui/jqueryui.d.ts
index 24f64ef34..9d8d17097 100644
--- a/jqueryui/jqueryui.d.ts
+++ b/jqueryui/jqueryui.d.ts
@@ -652,6 +652,7 @@ declare module JQueryUI {
         forceHelperSize?: boolean;
         forcePlaceholderSize?: boolean;
         grid?: number[];
+        helper?: string | ((event: Event, element: Sortable) => Element);
         handle?: any; // Selector or Element
         items?: any; // Selector
         opacity?: number;