diff --git a/includes/batch.inc b/includes/batch.inc
index 061acd4..5dec780 100644
--- a/includes/batch.inc
+++ b/includes/batch.inc
@@ -435,7 +435,17 @@ function _batch_next_set() {
   if (isset($batch['sets'][$batch['current_set'] + 1])) {
     $batch['current_set']++;
     $current_set = &_batch_current_set();
-    if (isset($current_set['form_submit']) && ($function = $current_set['form_submit']) && function_exists($function)) {
+    if (isset($current_set['form_submit']) && ($function = $current_set['form_submit'])) {
+      foreach ($batch['form_state']['build_info']['files'] as $file) {
+        if (is_array($file)) {
+          $file += array('type' => 'inc', 'name' => $file['module']);
+          module_load_include($file['type'], $file['module'], $file['name']);
+        }
+        elseif (file_exists($file)) {
+          require_once DRUPAL_ROOT . '/' . $file;
+        }
+      }
+      if (function_exists($function)) {
       // We use our stored copies of $form and $form_state to account for
       // possible alterations by previous form submit handlers.
       $function($batch['form_state']['complete form'], $batch['form_state']);