diff --git a/compass.inc b/compass.inc
index 6b90885..12e141a 100644
--- a/compass.inc
+++ b/compass.inc
@@ -49,7 +49,9 @@ function _compass_update($theme) {
   if (variable_get('compass_relative_assets', FALSE)) {
     $args['relative_assets'] = '';
   }
-  $args['load'] = getcwd() . '/' . dirname($themes[$theme->base_theme]->filename);
+  if (isset($theme->base_theme)) {
+    $args['load'] = getcwd() . '/' . dirname($themes[$theme->base_theme]->filename);
+  }
 
   drupal_alter('compass_options', $args, $op);
   return $command . ' ' . _compass_options($args);