diff --git a/modules/contrib/hierarchical_select/includes/theme.inc b/modules/contrib/hierarchical_select/includes/theme.inc
index e633f0a..1cd2a1e 100644
--- a/modules/contrib/hierarchical_select/includes/theme.inc
+++ b/modules/contrib/hierarchical_select/includes/theme.inc
@@ -67,7 +67,7 @@ function theme_hierarchical_select_form_element($variables) {
 function theme_hierarchical_select($variables) {
   $element = $variables['element'];
   $output = '';
-
+  
   // Update $element['#attributes']['class'].
   if (!isset($element['#attributes']['class'])) {
     $element['#attributes']['class'] = array();
@@ -83,8 +83,7 @@ function theme_hierarchical_select($variables) {
    'hierarchical-select-wrapper-for-name-' . $element['#id'],
    (isset($element['#config']['config_id'])) ? 'hierarchical-select-wrapper-for-config-' . $element['#config']['config_id'] : NULL,
   );
-  array_merge($element['#attributes']['class'], $classes);
-  $element['#attributes']['class'] .= ' ' . implode(' ', $classes);
+  $element['#attributes']['class'] = array_merge($element['#attributes']['class'], $classes);
   $element['#attributes']['id'] = "hierarchical-select-$hsid-wrapper";
   $element['#id'] = "hierarchical-select-$hsid-wrapper"; // This ensures the label's for attribute is correct.