diff --git a/src/proto/evalvars.pro b/src/proto/evalvars.pro
index 0861a88..ce160d7 100644
--- a/src/proto/evalvars.pro
+++ b/src/proto/evalvars.pro
@@ -70,7 +70,7 @@
 void vars_clear_ext(hashtab_T *ht, int free_val);
 void delete_var(hashtab_T *ht, hashitem_T *hi);
 void set_var(char_u *name, typval_T *tv, int copy);
-void set_var_const(char_u *name, type_T *type, typval_T *tv_arg, int copy, int flags);
+void set_var_const(char_u *name, type_T *type, typval_T *tv_arg, int copy, int flags, int var_idx);
 int var_check_permission(dictitem_T *di, char_u *name);
 int var_check_ro(int flags, char_u *name, int use_gettext);
 int var_check_lock(int flags, char_u *name, int use_gettext);