diff --git a/includes/common.inc b/includes/common.inc
index a05a09a7b16435f5db5ae6020d6c8fc971e1a527..a161667e177e870efb0612081992b3334292dfb2 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -1434,11 +1434,11 @@ function _filter_xss_attributes($attr) {
     switch ($mode) {
       case 0:
         // Attribute name, href for instance
-        if (preg_match('/^([-a-zA-Z]+)/', $attr, $match)) {
+        if (preg_match('/^([-a-zA-Z:]+)/', $attr, $match)) {
           $attrname = strtolower($match[1]);
           $skip = ($attrname == 'style' || substr($attrname, 0, 2) == 'on');
           $working = $mode = 1;
-          $attr = preg_replace('/^[-a-zA-Z]+/', '', $attr);
+          $attr = preg_replace('/^[-a-zA-Z:]+/', '', $attr);
         }
         break;