diff --git a/modules/pseudoTreeBuilder.js b/modules/pseudoTreeBuilder.js
index bf08faf8..5d63866f 100644
--- a/modules/pseudoTreeBuilder.js
+++ b/modules/pseudoTreeBuilder.js
@@ -38,10 +38,11 @@ const EXPORTED_SYMBOLS = ['PseudoTreeBuilder'];
 const Cc = Components.classes;
 const Ci = Components.interfaces;
 
-Components.utils.import('resource://treestyletab-modules/utils.js');
+Components.utils.import('resource://gre/modules/XPCOMUtils.jsm');
+
+XPCOMUtils.defineLazyModuleGetter(this, 'TreeStyleTabUtils', 'resource://treestyletab-modules/utils.js');
 
 var PseudoTreeBuilder = {
-	__proto__ : TreeStyleTabUtils,
 
 	kFAVICON      : 'treestyletab-pseudo-tree-favicon',
 	kROOTITEM     : 'treestyletab-pseudo-tree-root-item',
@@ -104,7 +105,7 @@ var PseudoTreeBuilder = {
 		if (w.isBlankPageURL ? !w.isBlankPageURL(uri) : (uri != 'about:blank')) tooltip += '\n' + uri;
 		label.setAttribute('tooltiptext', tooltip);
 		label.setAttribute('class', 'text-link '+this.kTREEITEM);
-		label.setAttribute('tab-id', this.getTabValue(aTab, this.kID));
+		label.setAttribute('tab-id', TreeStyleTabUtils.getTabValue(aTab, TreeStyleTabUtils.kID));
 
 		var children = this.createTabChildren(aTab);
 		if (children) {
@@ -122,7 +123,7 @@ var PseudoTreeBuilder = {
 	{
 		var doc = aTab.ownerDocument;
 
-		var children = this.getChildTabs(aTab);
+		var children = TreeStyleTabUtils.getChildTabs(aTab);
 		if (!children.length)
 			return null;