// If the user doesn't already belong to the blog, bail.
if ( !is_user_member_of_blog( $user_id ) )
- wp_die(__('Cheatin’ uh?'));
+ wp_die( __( 'Cheatin’ uh?' ), 403 );
$user = get_userdata( $user_id );
$user->set_role( $_REQUEST['new_role'] );