diff --git a/runtime/ftplugin/zsh.vim b/runtime/ftplugin/zsh.vim
index 0ca8077..ed75d04 100644
--- a/runtime/ftplugin/zsh.vim
+++ b/runtime/ftplugin/zsh.vim
@@ -30,7 +30,7 @@
     compiler zsh
   endif
   setlocal keywordprg=:RunHelp
-  let b:undo_ftplugin .= 'keywordprg<'
+  let b:undo_ftplugin .= 'keywordprg< | sil! delc -buffer RunHelp'
 endif
 
 let b:match_words = '\<if\>:\<elif\>:\<else\>:\<fi\>'