diff --git a/runtime/ftplugin/udevrules.vim b/runtime/ftplugin/udevrules.vim
index bde9c5d..83fb728 100644
--- a/runtime/ftplugin/udevrules.vim
+++ b/runtime/ftplugin/udevrules.vim
@@ -27,7 +27,7 @@
   if exists(':Sman') == 2
     setlocal iskeyword+=-
     setlocal keywordprg=:Sman
-    let b:undo_ftplugin .= '| setlocal keywordprg< iskeyword<'
+    let b:undo_ftplugin .= '| setlocal keywordprg< iskeyword< | sil! delc -buffer Sman'
   endif
 endif