diff --git a/content/treestyletab/windowHelperHacks.js b/content/treestyletab/windowHelperHacks.js
index 1d5762a1..21be2cf6 100644
--- a/content/treestyletab/windowHelperHacks.js
+++ b/content/treestyletab/windowHelperHacks.js
@@ -1,3 +1,5 @@
+Components.utils.import('resource://gre/modules/Services.jsm');
+
 TreeStyleTabWindowHelper.extraProperties = [
 	TreeStyleTabService.kID,
 	TreeStyleTabService.kCOLLAPSED,
@@ -1051,12 +1053,12 @@ TreeStyleTabWindowHelper.overrideExtensionsAfterBrowserInit = function TSTWH_ove
 			sv.getPref('extensions.stm.newTabPosition') != 0
 			) {
 			let checked = { value : false };
-			if (sv.PromptService.confirmEx(
+			if (Services.prompt.confirmEx(
 					null,
 					sv.treeBundle.getString('compatibility_STM_warning_title'),
 					sv.treeBundle.getString('compatibility_STM_warning_text'),
-					(sv.PromptService.BUTTON_TITLE_IS_STRING * sv.PromptService.BUTTON_POS_0) +
-					(sv.PromptService.BUTTON_TITLE_IS_STRING * sv.PromptService.BUTTON_POS_1),
+					(Services.prompt.BUTTON_TITLE_IS_STRING * Services.prompt.BUTTON_POS_0) +
+					(Services.prompt.BUTTON_TITLE_IS_STRING * Services.prompt.BUTTON_POS_1),
 					sv.treeBundle.getString('compatibility_STM_warning_use_TST'),
 					sv.treeBundle.getString('compatibility_STM_warning_use_STM'),
 					null,
diff --git a/modules/utils.js b/modules/utils.js
index ff725914..fb6b9cfb 100644
--- a/modules/utils.js
+++ b/modules/utils.js
@@ -277,15 +277,6 @@ var TreeStyleTabUtils = {
 	},
 	_SessionStore : null,
 
-	get PromptService()
-	{
-		if (!this._PromptService) {
-			this._PromptService = Services.prompt;
-		}
-		return this._PromptService;
-	},
-	_PromptService : null,
-
 	get FocusManager()
 	{
 		if (!this._FocusManager) {
@@ -678,11 +669,11 @@ var TreeStyleTabUtils = {
 		if (behavior & this.kDROPLINK_FIXED) return behavior;
 
 		var checked = { value : false };
-		var newChildTab = this.PromptService.confirmEx(this.browserWindow,
+		var newChildTab = Services.prompt.confirmEx(this.browserWindow,
 				this.treeBundle.getString('dropLinkOnTab.title'),
 				this.treeBundle.getString('dropLinkOnTab.text'),
-				(this.PromptService.BUTTON_TITLE_IS_STRING * this.PromptService.BUTTON_POS_0) +
-				(this.PromptService.BUTTON_TITLE_IS_STRING * this.PromptService.BUTTON_POS_1),
+				(Services.prompt.BUTTON_TITLE_IS_STRING * Services.prompt.BUTTON_POS_0) +
+				(Services.prompt.BUTTON_TITLE_IS_STRING * Services.prompt.BUTTON_POS_1),
 				this.treeBundle.getString('dropLinkOnTab.openNewChildTab'),
 				this.treeBundle.getString('dropLinkOnTab.loadInTheTab'),
 				null,
@@ -709,12 +700,12 @@ var TreeStyleTabUtils = {
 		var dummyTabFlag = behavior & this.kGROUP_BOOKMARK_USE_DUMMY;
 
 		var checked = { value : false };
-		var button = this.PromptService.confirmEx(this.browserWindow,
+		var button = Services.prompt.confirmEx(this.browserWindow,
 				this.treeBundle.getString('openGroupBookmarkBehavior.title'),
 				this.treeBundle.getString('openGroupBookmarkBehavior.text'),
-				(this.PromptService.BUTTON_TITLE_IS_STRING * this.PromptService.BUTTON_POS_0) +
-				(this.PromptService.BUTTON_TITLE_IS_STRING * this.PromptService.BUTTON_POS_1) +
-				(this.PromptService.BUTTON_TITLE_IS_STRING * this.PromptService.BUTTON_POS_2),
+				(Services.prompt.BUTTON_TITLE_IS_STRING * Services.prompt.BUTTON_POS_0) +
+				(Services.prompt.BUTTON_TITLE_IS_STRING * Services.prompt.BUTTON_POS_1) +
+				(Services.prompt.BUTTON_TITLE_IS_STRING * Services.prompt.BUTTON_POS_2),
 				this.treeBundle.getString('openGroupBookmarkBehavior.subTree'),
 				this.treeBundle.getString('openGroupBookmarkBehavior.separate'),
 				this.treeBundle.getString('openGroupBookmarkBehavior.replace'),
@@ -752,11 +743,11 @@ var TreeStyleTabUtils = {
 		if (behavior & this.kBOOKMARK_DROPPED_TABS_FIXED) return behavior;
 
 		var checked = { value : false };
-		var button = this.PromptService.confirmEx(this.browserWindow,
+		var button = Services.prompt.confirmEx(this.browserWindow,
 				this.treeBundle.getString('bookmarkDroppedTabs.title'),
 				this.treeBundle.getString('bookmarkDroppedTabs.text'),
-				(this.PromptService.BUTTON_TITLE_IS_STRING * this.PromptService.BUTTON_POS_0) +
-				(this.PromptService.BUTTON_TITLE_IS_STRING * this.PromptService.BUTTON_POS_1),
+				(Services.prompt.BUTTON_TITLE_IS_STRING * Services.prompt.BUTTON_POS_0) +
+				(Services.prompt.BUTTON_TITLE_IS_STRING * Services.prompt.BUTTON_POS_1),
 				this.treeBundle.getString('bookmarkDroppedTabs.bookmarkAll'),
 				this.treeBundle.getString('bookmarkDroppedTabs.bookmarkOnlyParent'),
 				null,
diff --git a/modules/window.js b/modules/window.js
index 8715c1a6..86305118 100644
--- a/modules/window.js
+++ b/modules/window.js
@@ -1388,11 +1388,11 @@ TreeStyleTabWindow.prototype = {
 		var checked = { value:true };
 		var w = this.window;
 		w.focus();
-		var shouldClose = this.PromptService.confirmEx(w,
+		var shouldClose = Services.prompt.confirmEx(w,
 				this.tabbrowserBundle.getString('tabs.closeWarningTitle'),
 				this.tabbrowserBundle.getFormattedString('tabs.closeWarningMultipleTabs', [aTabsCount]),
-				(this.PromptService.BUTTON_TITLE_IS_STRING * this.PromptService.BUTTON_POS_0) +
-				(this.PromptService.BUTTON_TITLE_CANCEL * this.PromptService.BUTTON_POS_1),
+				(Services.prompt.BUTTON_TITLE_IS_STRING * Services.prompt.BUTTON_POS_0) +
+				(Services.prompt.BUTTON_TITLE_CANCEL * Services.prompt.BUTTON_POS_1),
 				this.tabbrowserBundle.getString('tabs.closeButtonMultiple'),
 				null, null,
 				this.tabbrowserBundle.getString('tabs.closeWarningPromptMe'),