Index: wp-admin/includes/class-wp-screen.php
===================================================================
--- wp-admin/includes/class-wp-screen.php	(revision 36049)
+++ wp-admin/includes/class-wp-screen.php	(working copy)
@@ -530,7 +530,7 @@
 			}
 		}
 
-		sort( $priorities );
+		ksort( $priorities );
 
 		$sorted = array();
 		foreach ( $priorities as $list ) {