--- thrifty404.module
+++ (clipboard)
@@ -20,7 +20,7 @@
 
   if (user_access('search content')) {
     $path = $_REQUEST['destination'];
-    $keys = strtolower(preg_replace('/[^a-zA-Z0-9-]+/', ' ', $path));
+    $keys = strtolower(preg_replace('/[^a-zA-Z0-9]+/', ' ', $path));
 
     $thrifty404_content = $thrifty404_message . drupal_get_form('search_form', NULL, $keys, 'node', $thrifty404_prompt);
   }