diff --git a/ui/jquery.ui.mouse.js b/ui/jquery.ui.mouse.js
index 6f95765f2..dc10d9401 100644
--- a/ui/jquery.ui.mouse.js
+++ b/ui/jquery.ui.mouse.js
@@ -47,9 +47,11 @@ $.widget("ui.mouse", {
 	// other instances of mouse
 	_mouseDestroy: function() {
 		this.element.unbind('.'+this.widgetName);
-		$(document)
-			.unbind('mousemove.'+this.widgetName, this._mouseMoveDelegate)
-			.unbind('mouseup.'+this.widgetName, this._mouseUpDelegate);
+		if ( this._mouseMoveDelegate ) {
+			$(document)
+				.unbind('mousemove.'+this.widgetName, this._mouseMoveDelegate)
+				.unbind('mouseup.'+this.widgetName, this._mouseUpDelegate);
+		}
 	},
 
 	_mouseDown: function(event) {