diff --git a/etemplate/js/et2_core_inheritance.js b/etemplate/js/et2_core_inheritance.js
index 2e7a4e5a9e..f0559f0640 100644
--- a/etemplate/js/et2_core_inheritance.js
+++ b/etemplate/js/et2_core_inheritance.js
@@ -477,7 +477,7 @@
 	Class.prototype.initAttributes = function(_attrs) {
 		for (var key in _attrs)
 		{
-			if (!this.attributes[key].ignore && !(_attrs[key] == undefined))
+			if (typeof this.attributes[key] != "undefined" && !this.attributes[key].ignore && !(_attrs[key] == undefined))
 			{
 				this.setAttribute(key, _attrs[key], false);
 			}