diff --git a/src/proto/screen.pro b/src/proto/screen.pro
index b4f54a2..53937d3 100644
--- a/src/proto/screen.pro
+++ b/src/proto/screen.pro
@@ -55,8 +55,8 @@
 int number_width(win_T *wp);
 int screen_screencol(void);
 int screen_screenrow(void);
-char *set_fillchars_option(win_T *wp, char_u *val, int apply);
-char *set_listchars_option(win_T *wp, char_u *val, int apply);
+char *set_fillchars_option(win_T *wp, char_u *val, int apply, char *errbuf, size_t errbuflen);
+char *set_listchars_option(win_T *wp, char_u *val, int apply, char *errbuf, size_t errbuflen);
 char_u *get_fillchars_name(expand_T *xp, int idx);
 char_u *get_listchars_name(expand_T *xp, int idx);
 char *check_chars_options(void);