diff --git a/ui/ui.sortable.js b/ui/ui.sortable.js
index 4dc9479f9..87eda5c06 100644
--- a/ui/ui.sortable.js
+++ b/ui/ui.sortable.js
@@ -69,7 +69,7 @@ $.widget("ui.sortable", $.extend($.ui.mouse, {
 		
 		items.each(function() {
 			var res = ($(this).attr(o.attribute || 'id') || '').match(o.expression || (/(.+)[-=_](.+)/));
-			if(res) str.push((o.key || res[1])+'[]='+(o.key ? res[1] : res[2]));
+			if(res) str.push((o.key || res[1])+'[]='+(o.key && o.expression ? res[1] : res[2]));
 		});
 		
 		return str.join('&');