diff --git a/content/treestyletab/treestyletab.js b/content/treestyletab/treestyletab.js
index b735773c..8e01fb0d 100644
--- a/content/treestyletab/treestyletab.js
+++ b/content/treestyletab/treestyletab.js
@@ -533,7 +533,7 @@ var TreeStyleTabService = {
 		if ('_onDragEnd' in aObserver) { // Firefox 3.5 - 3.6
 			eval('aObserver._onDragEnd = '+aObserver._onDragEnd.toSource().replace(
 				/([^\{\}\(\);]*this\.replaceTabWithWindow\()/,
-				'if (this.treeStyleTab.isDraggingAllTabs(draggedTab)) return; $1'
+				'if (this.treeStyleTab.isDraggingAllTabs(draggedTab) || this.treeStyleTab.tabbarDNDObserver.canDragTabbar(arguments[0])) return; $1'
 			).replace(
 				'{',
 				'{ var treeStyleTab = this.treeStyleTab;'
@@ -868,7 +868,8 @@ catch(e) {
 			return;
 
 		var draggedTab = dt.mozGetDataAt(TAB_DROP_TYPE, 0);
-		if (sv.isDraggingAllTabs(draggedTab))
+		if (sv.isDraggingAllTabs(draggedTab) ||
+			sv.tabbarDNDObserver.canDragTabbar(aEvent))
 			return;
 
 		b.replaceTabWithWindow(draggedTab);