diff --git a/autosave.module b/autosave.module
index 976246f..3853337 100644
--- a/autosave.module
+++ b/autosave.module
@@ -183,6 +183,11 @@ function autosave_form_alter(&$form, &$form_state, $form_id) {
   if (($autosave_node_form || in_array($form_id, $form_ids))) {
     // Remove the autosaved form when submitting it.
     array_unshift($form['#submit'], 'autosave_remove_autosaved_form_submit');
+
+    // Autosaved forms need to be cached so that $form_state can be retrieved
+    // with ajax_get_form() during save.
+    $form_state['cache'] = TRUE;
+
     if (empty($_POST['autosave_form_path'])) {
       $request_path = request_path();
       // We store the drupal system paths, not the aliases.
@@ -281,21 +286,22 @@ function autosave_restore($form_id, $timestamp) {
   $commands = array();
 
   if ($record) {
-    $form_state = array();
-    // We need to extract and reuse any additional page arguments that the
-    // original form may have.  That's especially true for, say, a node form,
-    // which needs the node object passed in as well.
-    $menu_item = autosave_menu_get_item($record->path);
-    if ($menu_item['include_file']) {
-      require_once DRUPAL_ROOT . '/' . $menu_item['include_file'];
-      $form_state['build_info']['files'][] = $menu_item['include_file'];
-    }
-    $form_state['input'] = unserialize($record->serialized);
-
-    // Restore form arguments.
-    if (!empty($record->args)) {
-      $args = unserialize($record->args);
-      $form_state['build_info']['args'] = $args;
+    $form_state = unserialize($record->serialized);
+
+    // Manually load include files that the form depends on. Normally this will
+    // be handled automatically by form_get_cache() (which this code is copied
+    // from) but if the autosaved data is old enough that the cache_form entry
+    // is no longer present, it needs to be done manually.
+    if (!empty($form_state['build_info']['files'])) {
+      foreach ($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;
+       }
+      }
     }
 
     // Disable the "this form has already been submitted" nonsense by making
@@ -390,11 +396,10 @@ function autosave_save() {
   $prevent_autosave = FALSE;
   drupal_alter('autosave_prevent', $prevent_autosave);
 
-  $path = $_POST['autosave_form_path'];
-  $form_id = $_POST['form_id'];
-  // Not all variables need to be serialized.
-  unset($_POST['autosave_form_path'], $_POST['op'], $_POST['form_build_id']);
-  $serialized = serialize($_POST);
+  list($form, $form_state) = ajax_get_form();
+  $path = $form_state['input']['autosave_form_path'];
+  $form_id = $form_state['input']['form_id'];
+  $serialized = serialize($form_state);
 
   if (!$prevent_autosave) {
     // Currently, each user can have only one autosave form at a particular path.