diff --git a/date/date_elements.inc b/date/date_elements.inc
index 6616817..a721055 100644
--- a/date/date_elements.inc
+++ b/date/date_elements.inc
@@ -580,7 +580,9 @@ function theme_date_combo($element) {
     '#collapsible' => FALSE,
     '#collapsed' => FALSE,
     '#description' => $element['#fieldset_description'],
-    '#attributes' => array(),
+    '#attributes' => array(
+      'class' => str_replace('_', '-', $field['field_name'] . '-field-wrapper'),
+    ),
   );
   return theme('fieldset', $fieldset);
 }