diff --git a/core/model/SiteTree.php b/core/model/SiteTree.php
index 69130e0e1..f8f582c40 100644
--- a/core/model/SiteTree.php
+++ b/core/model/SiteTree.php
@@ -1118,6 +1118,9 @@ class SiteTree extends DataObject implements PermissionProvider,i18nEntityProvid
 	 */
 	function getCMSFields() {
 		require_once("forms/Form.php");
+		Requirements::javascript(THIRDPARTY_DIR . "/prototype.js");
+		Requirements::javascript(THIRDPARTY_DIR . "/behaviour.js");
+		Requirements::javascript(THIRDPARTY_DIR . "/behaviour_improvements.js");
 		Requirements::javascript(CMS_DIR . "/javascript/SitetreeAccess.js");
 		Requirements::add_i18n_javascript(SAPPHIRE_DIR . '/javascript/lang');
 		Requirements::javascript(SAPPHIRE_DIR . '/javascript/UpdateURL.js');