diff -Naurp php-5.5.9/ext/simplexml/simplexml.c php-5.5.9.oden/ext/simplexml/simplexml.c
--- php-5.5.9/ext/simplexml/simplexml.c	2014-02-05 11:00:36.000000000 +0100
+++ php-5.5.9.oden/ext/simplexml/simplexml.c	2014-02-12 11:28:36.226857491 +0100
@@ -1660,6 +1660,13 @@ SXE_METHOD(addChild)
 
 	localname = xmlSplitQName2((xmlChar *)qname, &prefix);
 	if (localname == NULL) {
+		if (nsuri_len > 0) {
+			if (prefix != NULL) {
+				xmlFree(prefix);
+			}
+			php_error_docref(NULL TSRMLS_CC, E_WARNING, "Attribute requires prefix for namespace");
+			return;
+		}
 		localname = xmlStrdup((xmlChar *)qname);
 	}