diff --git a/src/optionstr.c b/src/optionstr.c
index 1329be3..1665509 100644
--- a/src/optionstr.c
+++ b/src/optionstr.c
@@ -1562,7 +1562,7 @@
  * The 'guifont' option is changed.
  */
     static char *
-did_set_guifont(char_u *oldval, int *redraw_gui_only)
+did_set_guifont(char_u *oldval UNUSED, int *redraw_gui_only)
 {
     char_u	*p;
     char	*errmsg = NULL;