diff --git a/chrome/content/zotero/zoteroPane.js b/chrome/content/zotero/zoteroPane.js
index 10ad337be..829bad478 100644
--- a/chrome/content/zotero/zoteroPane.js
+++ b/chrome/content/zotero/zoteroPane.js
@@ -3159,7 +3159,7 @@ var ZoteroPane = new function()
 	
 	
 	this.addItemFromURL = function (url, itemType, saveSnapshot, row) {
-		if (url == window.content.document.location.href) {
+		if (window.content && url == window.content.document.location.href) {
 			return this.addItemFromPage(itemType, saveSnapshot, row);
 		}