diff --git a/src/proto/vim9compile.pro b/src/proto/vim9compile.pro
index 03f7df1..e6c6f3e 100644
--- a/src/proto/vim9compile.pro
+++ b/src/proto/vim9compile.pro
@@ -16,6 +16,7 @@
 int may_get_next_line_error(char_u *whitep, char_u **arg, cctx_T *cctx);
 void fill_exarg_from_cctx(exarg_T *eap, cctx_T *cctx);
 int func_needs_compiling(ufunc_T *ufunc, compiletype_T compile_type);
+char_u *compile_one_expr_in_str(char_u *p, cctx_T *cctx);
 int compile_all_expr_in_str(char_u *str, int evalstr, cctx_T *cctx);
 int assignment_len(char_u *p, int *heredoc);
 void vim9_declare_error(char_u *name);