diff --git a/mod/folder/edit_form.php b/mod/folder/edit_form.php
index 85f9ca57a2d..309ae9f2e57 100644
--- a/mod/folder/edit_form.php
+++ b/mod/folder/edit_form.php
@@ -36,6 +36,7 @@ class mod_folder_edit_form extends moodleform {
         $options = $this->_customdata['options'];
 
         $mform->addElement('hidden', 'id', $data->id);
+        $mform->setType('id', PARAM_INT);
         $mform->addElement('filemanager', 'files_filemanager', get_string('files'), null, $options);
         $submit_string = get_string('savechanges');
         $this->add_action_buttons(true, $submit_string);