Index: search404.module
===================================================================
--- search404.module    (revision 1694)
+++ search404.module    (working copy)
@@ -38,7 +38,7 @@
   if (!empty($extensions) && preg_match("/\.($extensions)$/", $_REQUEST['destination'])) {
     return false;
   }
-  $keys = $_REQUEST['destination'];
+  $keys = $_REQUEST['q'];
   $misc_var = variable_get('search404_regex', '');
   if (!empty($misc_var)) {
        $keys = preg_grep($misc_var, $keys);