diff --git a/lib/yui/dragdrop/dragdrop.js b/lib/yui/dragdrop/dragdrop.js
index 20c3a818b4a..c46205b7c1b 100644
--- a/lib/yui/dragdrop/dragdrop.js
+++ b/lib/yui/dragdrop/dragdrop.js
@@ -167,6 +167,10 @@ YUI.add('moodle-core-dragdrop', function(Y) {
             // this.lastdroptarget (ghost node we use for indicating where to drop)
             e.drag = e.target;
             e.drop = this.lastdroptarget;
+            // Check that drag object belongs to correct group
+            if (!this.in_group(e.drag)) {
+                return;
+            }
             // Check that drop object belong to correct group
             if (!e.drop || !e.drop.inGroup(this.groups)) {
                 return;