diff --git a/advanced_help.module b/advanced_help.module
index aae5cb2..b538ee5 100644
--- a/advanced_help.module
+++ b/advanced_help.module
@@ -999,6 +999,7 @@ function template_preprocess_advanced_help_popup(&$variables) {
   $css = drupal_add_css();
 
   // Remove theme css.
+  $exclude = array();
   foreach ($css as $key => $value) {
     if ($value['group'] == CSS_THEME) {
       $exclude[$key] = FALSE;