diff --git a/runtime/indent/nginx.vim b/runtime/indent/nginx.vim
index d4afec1..8cef766 100644
--- a/runtime/indent/nginx.vim
+++ b/runtime/indent/nginx.vim
@@ -1,7 +1,7 @@
 " Vim indent file
 " Language: nginx.conf
 " Maintainer: Chris Aumann <me@chr4.org>
-" Last Change: Apr 15, 2017
+" Last Change:  2022 Apr 06
 
 if exists("b:did_indent")
     finish
@@ -15,3 +15,5 @@
 
 " Just make sure that the comments are not reset as defs would be.
 setlocal cinkeys-=0#
+
+let b:undo_indent = "setl inde< cin< cink<"