diff --git a/src/proto/fileio.pro b/src/proto/fileio.pro
index 8b05113..2f5897c 100644
--- a/src/proto/fileio.pro
+++ b/src/proto/fileio.pro
@@ -22,6 +22,7 @@
 char_u *vim_tempname __ARGS((int extra_char));
 void forward_slash __ARGS((char_u *fname));
 void aubuflocal_remove __ARGS((buf_T *buf));
+int au_has_group __ARGS((char_u *name));
 void do_augroup __ARGS((char_u *arg, int del_group));
 void free_all_autocmds __ARGS((void));
 int check_ei __ARGS((void));