diff --git a/ds.api.php b/ds.api.php
index fbf3efb..59aa495 100644
--- a/ds.api.php
+++ b/ds.api.php
@@ -420,9 +420,12 @@ function hook_ds_layout_info() {
  *   - entity_type
  *   - bundle
  *   - view_mode
+ * @param array $vars
+ *   All variables available for render. You can use this to add css classes.
  */
-function hook_ds_pre_render_alter(&$layout_render_array, $context) {
+function hook_ds_pre_render_alter(&$layout_render_array, $context, &$vars) {
   $layout_render_array['left'][] = array('#markup' => 'cool!', '#weight' => 20);
+  $vars['attributes_array']['class'][] = 'custom';
 }
 
 /**
diff --git a/ds.module b/ds.module
index 9764305..03dd105 100644
--- a/ds.module
+++ b/ds.module
@@ -812,7 +812,7 @@ function ds_entity_variables(&$vars) {
 
     // Let other modules alter the ds array before creating the region variables.
     $context = array('entity' => isset($vars[$object]) ? $vars[$object] : (isset($vars['elements']['#' . $object]) ? $vars['elements']['#' . $object] : ''), 'entity_type' => $vars['elements']['#entity_type'], 'bundle' => $vars['elements']['#bundle'], 'view_mode' => $vars['elements']['#view_mode']);
-    drupal_alter('ds_pre_render', $layout_render_array, $context);
+    drupal_alter('ds_pre_render', $layout_render_array, $context, $vars);
     foreach ($layout_render_array as $region_name => $content) {
       // In case this is a panels layout, add the region to the $content variable.
       if (isset($layout['module']) && $layout['module'] == 'panels') {