diff --git a/src/proto/vim9script.pro b/src/proto/vim9script.pro
index 3a7b6e1..a11f6af 100644
--- a/src/proto/vim9script.pro
+++ b/src/proto/vim9script.pro
@@ -7,5 +7,5 @@
 int find_exported(int sid, char_u **argp, int *name_len, ufunc_T **ufunc, type_T **type);
 char_u *handle_import(char_u *arg_start, garray_T *gap, int import_sid, void *cctx);
 char_u *vim9_declare_scriptvar(exarg_T *eap, char_u *arg);
-void check_script_var_type(typval_T *dest, typval_T *value, char_u *name);
+int check_script_var_type(typval_T *dest, typval_T *value, char_u *name);
 /* vim: set ft=c : */