diff --git a/wp-admin/includes/admin.php b/wp-admin/includes/admin.php
index a75a19934d..935372c8b4 100644
--- a/wp-admin/includes/admin.php
+++ b/wp-admin/includes/admin.php
@@ -51,4 +51,8 @@ require_once(ABSPATH . 'wp-admin/includes/update.php');
 /** WordPress Registration API */
 require_once(ABSPATH . WPINC . '/registration.php');
 
-?>
\ No newline at end of file
+/** WordPress Multi-Site support API */
+if ( is_multisite() )
+	require_once(ABSPATH . 'wp-admin/includes/ms.php');
+
+?>