diff --git a/src/proto/vim9script.pro b/src/proto/vim9script.pro
index bc1e232..04c07fc 100644
--- a/src/proto/vim9script.pro
+++ b/src/proto/vim9script.pro
@@ -16,7 +16,7 @@
 char_u *vim9_declare_scriptvar(exarg_T *eap, char_u *arg);
 void update_vim9_script_var(int create, dictitem_T *di, char_u *name, int flags, typval_T *tv, type_T **type, int do_member);
 void hide_script_var(scriptitem_T *si, int idx, int func_defined);
-svar_T *find_typval_in_script(typval_T *dest, scid_T sid);
+svar_T *find_typval_in_script(typval_T *dest, scid_T sid, int must_find);
 int check_script_var_type(svar_T *sv, typval_T *value, char_u *name, where_T where);
 int check_reserved_name(char_u *name);
 /* vim: set ft=c : */