diff --git a/core/includes/common.inc b/core/includes/common.inc
index ca1eeaf..051fbe8 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -3829,7 +3829,9 @@ function drupal_render(&$elements) {
     $children_keys = element_children($elements);
     $output = '';
     foreach ($children_keys as $key) {
-      $output .= drupal_render($element[$key]);
+      if (!empty($elements[$key])) {
+        $output .= drupal_render($elements[$key]);
+      }
     }
     return $output;
   }