diff --git a/runtime/indent/yacc.vim b/runtime/indent/yacc.vim
index 01ad4fc..253ccc5 100644
--- a/runtime/indent/yacc.vim
+++ b/runtime/indent/yacc.vim
@@ -1,7 +1,8 @@
 " Vim indent file
-" Language:             YACC input file
-" Previous Maintainer:  Nikolai Weibull <now@bitwi.se>
-" Latest Revision:      2006-12-20
+" Language:		YACC input file
+" Maintainer:		Doug Kearns <dougkearns@gmail.com>
+" Previous Maintainer:	Nikolai Weibull <now@bitwi.se>
+" Last Change:		2022 April 25
 
 " Only load this indent file when no other was loaded.
 if exists("b:did_indent")
@@ -14,6 +15,8 @@
 setlocal indentkeys=!^F,o,O
 setlocal nosmartindent
 
+let b:undo_indent = "setl inde< indk< si<"
+
 " Only define the function once.
 if exists("*GetYaccIndent")
   finish