diff --git a/src/proto/vim9compile.pro b/src/proto/vim9compile.pro
index 04c3c5e..410910f 100644
--- a/src/proto/vim9compile.pro
+++ b/src/proto/vim9compile.pro
@@ -1,4 +1,5 @@
 /* vim9compile.c */
+int script_var_exists(char_u *name, size_t len, int vim9script, cctx_T *cctx);
 int check_defined(char_u *p, size_t len, cctx_T *cctx);
 int check_compare_types(exprtype_T type, typval_T *tv1, typval_T *tv2);
 int use_typecheck(type_T *actual, type_T *expected);