diff --git a/runtime/ftplugin/lprolog.vim b/runtime/ftplugin/lprolog.vim
index a8a3c61..1075a9c 100644
--- a/runtime/ftplugin/lprolog.vim
+++ b/runtime/ftplugin/lprolog.vim
@@ -2,7 +2,8 @@
 " Language:     LambdaProlog (Teyjus)
 " Maintainer:   Markus Mottl  <markus.mottl@gmail.com>
 " URL:          http://www.ocaml.info/vim/ftplugin/lprolog.vim
-" Last Change:  2006 Feb 05
+" Last Change:  2023 Aug 28 - added undo_ftplugin (Vim Project)
+"               2006 Feb 05
 "               2001 Sep 16 - fixed 'no_mail_maps'-bug (MM)
 "               2001 Sep 02 - initial release  (MM)
 
@@ -15,11 +16,13 @@
 let b:did_ftplugin = 1
 
 " Error format
-setlocal efm=%+A./%f:%l.%c:\ %m formatprg=fmt\ -w75\ -p\\%
+setlocal efm=%+A./%f:%l.%c:\ %m
 
 " Formatting of comments
 setlocal formatprg=fmt\ -w75\ -p\\%
 
+let b:undo_ftplugin = "setlocal efm< fp<"
+
 " Add mappings, unless the user didn't want this.
 if !exists("no_plugin_maps") && !exists("no_lprolog_maps")
   " Uncommenting
@@ -28,6 +31,11 @@
     vmap <buffer> <LocalLeader>c <Plug>BUncomOn
     nmap <buffer> <LocalLeader>C <Plug>LUncomOff
     vmap <buffer> <LocalLeader>C <Plug>BUncomOff
+    let b:undo_ftplugin ..=
+          \ " | silent! execute 'nunmap <buffer> <LocalLeader>c'" ..
+          \ " | silent! execute 'vunmap <buffer> <LocalLeader>c'" ..
+          \ " | silent! execute 'nunmap <buffer> <LocalLeader>C'" ..
+          \ " | silent! execute 'vunmap <buffer> <LocalLeader>C'"
   endif
 
   nnoremap <buffer> <Plug>LUncomOn mz0i/* <ESC>$A */<ESC>`z