diff --git a/ad_manager.module b/ad_manager.module
index 340ff51..6ddeb35 100644
--- a/ad_manager.module
+++ b/ad_manager.module
@@ -20,7 +20,7 @@ function ad_manager_block_info() {
  */
 function ad_manager_block_view($delta = '') {
   return array(
-    'content' => theme('ad_manager_ad', $delta),
+    'content' => theme('ad_manager_ad', array('name' => $delta)),
   );
 }

@@ -173,11 +173,12 @@ function ad_manager_theme($existing, $type, $theme, $path) {
 /**
  * Theme ads.
  */
-function theme_ad_manager_ad($name = NULL) {
+function theme_ad_manager_ad($vars) {
+  $name = $vars['name'];
   // Support multiple instances of a block on a page with incrementing index.
   static $index = array();

-  if ($name) {
+  if (strlen($name) > 0) {
     //Load the ad based on name.
     $ad = ad_manager_ctools_ad_load($name);