diff --git a/content/treestyletab/treestyletabbrowser.js b/content/treestyletab/treestyletabbrowser.js
index 0a3255c0..b0470b22 100644
--- a/content/treestyletab/treestyletabbrowser.js
+++ b/content/treestyletab/treestyletabbrowser.js
@@ -4045,7 +4045,7 @@ TreeStyleTabBrowser.prototype = {
 	{
 		/* PUBLIC API */
 		var event = document.createEvent('Events');
-		event.initEvent('TreeStyleTabAttached', true, false);
+		event.initEvent(this.kEVENT_TYPE_ATTACHED, true, false);
 		event.parentTab = aParent;
 		aChild.dispatchEvent(event);
 	},
@@ -4089,7 +4089,7 @@ TreeStyleTabBrowser.prototype = {
 
 		/* PUBLIC API */
 		var event = document.createEvent('Events');
-		event.initEvent('TreeStyleTabParted', true, false);
+		event.initEvent(this.kEVENT_TYPE_DETACHED, true, false);
 		event.parentTab = parentTab;
 		aChild.dispatchEvent(event);
 
diff --git a/modules/utils.js b/modules/utils.js
index 911ec66e..1baf9921 100644
--- a/modules/utils.js
+++ b/modules/utils.js
@@ -130,6 +130,8 @@ var TreeStyleTabUtils = {
 	kEVENT_TYPE_TABBAR_STATE_CHANGING        : 'TreeStyleTabTabbarStateChanging',
 	kEVENT_TYPE_TABBAR_STATE_CHANGED         : 'TreeStyleTabTabbarStateChanged',
 	kEVENT_TYPE_FOCUS_NEXT_TAB               : 'TreeStyleTabFocusNextTab',
+	kEVENT_TYPE_ATTACHED                     : 'TreeStyleTabAttached',
+	kEVENT_TYPE_DETACHED                     : 'TreeStyleTabParted',
 
 	kEVENT_TYPE_PRINT_PREVIEW_ENTERED        : 'TreeStyleTabPrintPreviewEntered',
 	kEVENT_TYPE_PRINT_PREVIEW_EXITED         : 'TreeStyleTabPrintPreviewExited',