diff --git a/content/treestyletab/hacks.js b/content/treestyletab/hacks.js
index 1c65f04c..3ef49c01 100644
--- a/content/treestyletab/hacks.js
+++ b/content/treestyletab/hacks.js
@@ -1227,6 +1227,7 @@ TreeStyleTabService.overrideExtensionsDelayed = function TSTService_overrideExte
 							personalTitlebar.removeAttribute('height');
 							personalTitlebar.removeAttribute('width');
 							personalTitlebar.removeAttribute('ordinal');
+							personalTitlebar.removeAttribute('orient');
 							break;
 
 						case 'aftercustomization':
diff --git a/content/treestyletab/treestyletabbrowser.js b/content/treestyletab/treestyletabbrowser.js
index 22fd679f..d3667772 100644
--- a/content/treestyletab/treestyletabbrowser.js
+++ b/content/treestyletab/treestyletabbrowser.js
@@ -1726,6 +1726,7 @@ TreeStyleTabBrowser.prototype = {
 		this.removeTabStripAttribute('width');
 		this.removeTabStripAttribute('height');
 		this.removeTabStripAttribute('ordinal');
+		this.removeTabStripAttribute('orient');
 
 		this._endListenTabbarEvents();