diff --git a/runtime/ftplugin/c.vim b/runtime/ftplugin/c.vim
index 378d580..915861b 100644
--- a/runtime/ftplugin/c.vim
+++ b/runtime/ftplugin/c.vim
@@ -44,7 +44,7 @@
 " When the matchit plugin is loaded, this makes the % command skip parens and
 " braces in comments properly.
 if !exists("b:match_words")
-  let b:match_words = '^\s*#\s*if\(\|def\|ndef\)\>:^\s*#\s*elif\>:^\s*#\s*else\>:^\s*#\s*endif\>'
+  let b:match_words = '^\s*#\s*if\%(\|def\|ndef\)\>:^\s*#\s*elif\%(\|def\|ndef\)\>:^\s*#\s*else\>:^\s*#\s*endif\>'
   let b:match_skip = 's:comment\|string\|character\|special'
   let b:undo_ftplugin ..= " | unlet! b:match_skip b:match_words"
 endif