diff --git a/content/treestyletab/treestyletab.js b/content/treestyletab/treestyletab.js
index 8a0181b4..20152cfa 100644
--- a/content/treestyletab/treestyletab.js
+++ b/content/treestyletab/treestyletab.js
@@ -877,7 +877,7 @@ var TreeStyleTabService = {
 	
 	getTabValue : function(aTab, aKey) 
 	{
-		var value = null;
+		var value = '';
 		try {
 			value = this.SessionStore.getTabValue(aTab, aKey);
 		}
diff --git a/content/treestyletab/treestyletabbrowser.js b/content/treestyletab/treestyletabbrowser.js
index 38124f81..419e3216 100644
--- a/content/treestyletab/treestyletabbrowser.js
+++ b/content/treestyletab/treestyletabbrowser.js
@@ -1640,7 +1640,7 @@ TreeStyleTabBrowser.prototype = {
 			nextTab = this.redirectId(nextTab);
 		}
 
-		var ancestors = (this.getTabValue(tab, this.kANCESTOR) || this.getTabValue(tab, this.kPARENT) || '').split('|');
+		var ancestors = (this.getTabValue(tab, this.kANCESTOR) || this.getTabValue(tab, this.kPARENT)).split('|');
 		var parent = null;
 		for (var i in ancestors)
 		{