diff --git a/lib/ace/edit_session/folding.js b/lib/ace/edit_session/folding.js
index d3fa0ef0..474818b2 100644
--- a/lib/ace/edit_session/folding.js
+++ b/lib/ace/edit_session/folding.js
@@ -747,8 +747,11 @@ function Folding() {
         };
         
         var range = this.$toggleFoldWidget(row, options);
-        if (!range)
-            (e.target || e.srcElement).className += " ace_invalid";
+        if (!range) {
+            var el = (e.target || e.srcElement)
+            if (el && /ace_fold-widget/.test(el.className))
+                el.className += " ace_invalid";
+        }
     };
     
     this.$toggleFoldWidget = function(row, options) {