--- zen/template.php.orig	2008-02-26 17:00:59.000000000 -0800
+++ zen/template.php	2008-02-26 18:38:29.000000000 -0800
@@ -130,7 +130,7 @@
   }
   // Optionally add the wireframes style.
   if (theme_get_setting('zen_wireframes')) {
-    drupal_add_css(path_to_zentheme() .'/wireframes.css', 'theme', 'all');
+    drupal_add_css($vars['directory'] .'/wireframes.css', 'theme', 'all');
   }
   $vars['css'] = drupal_add_css();
   $vars['styles'] = drupal_get_css();