diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index eca63fd..a98a1b7 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -862,6 +862,9 @@ function template_preprocess_datetime_form(&$variables) {
   if (isset($element['#id'])) {
     $variables['attributes']['id'] = $element['#id'];
   }
+  if (!empty($element['#attributes']['class'])) {
+    $variables['attributes']['class'] = (array) $element['#attributes']['class'];
+  }
 
   $variables['content'] = $element;
 }
@@ -890,7 +893,7 @@ function template_preprocess_datetime_wrapper(&$variables) {
   // For required datetime fields a 'form-required' class is appended to the
   // label attributes.
   if (!empty($element['#required'])) {
-    $variables['required'] = 1;
+    $variables['required'] = TRUE;
   }
   $variables['content'] = $element['#children'];
 }