diff --git a/runtime/indent/ch.vim b/runtime/indent/ch.vim
index e1bd8a3..11b1f67 100644
--- a/runtime/indent/ch.vim
+++ b/runtime/indent/ch.vim
@@ -3,6 +3,7 @@
 " Maintainer:	SoftIntegration, Inc. <info@softintegration.com>
 " URL:		http://www.softintegration.com/download/vim/indent/ch.vim
 " Last change:	2006 Apr 30
+" 		2023 Aug 28 by Vim Project (undo_indent)
 "		Created based on cpp.vim
 "
 " Ch is a C/C++ interpreter with many high level extensions
@@ -16,3 +17,5 @@
 
 " Ch indenting is built-in, thus this is very simple
 setlocal cindent
+
+let b:undo_indent = "setlocal cindent<"