diff --git a/src/proto/evalvars.pro b/src/proto/evalvars.pro
index 661cb59..9879a40 100644
--- a/src/proto/evalvars.pro
+++ b/src/proto/evalvars.pro
@@ -75,6 +75,7 @@
 void vars_clear(hashtab_T *ht);
 void vars_clear_ext(hashtab_T *ht, int free_val);
 void delete_var(hashtab_T *ht, hashitem_T *hi);
+int before_set_vvar(char_u *varname, dictitem_T *di, typval_T *tv, int copy, int *type_error);
 void set_var(char_u *name, typval_T *tv, int copy);
 void set_var_const(char_u *name, scid_T sid, type_T *type_arg, typval_T *tv_arg, int copy, int flags_arg, int var_idx);
 int var_check_permission(dictitem_T *di, char_u *name);