diff --git a/includes/common.inc b/includes/common.inc
index 3d73784..a7c7e20 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -652,6 +652,9 @@ function drupal_error_handler($errno, $message, $filename, $line, $context) {
       }
     }
 
+    if (!function_exists('filter_xss')) {
+      drupal_load('module', 'filter');
+    }
     $entry = check_plain($types[$errno]) .': '. filter_xss($message) .' in '. check_plain($filename) .' on line '. check_plain($line) .'.';
 
     // Force display of error messages in update.php.