diff --git a/src/proto/vim9execute.pro b/src/proto/vim9execute.pro
index 755b7dd..2f0ef54 100644
--- a/src/proto/vim9execute.pro
+++ b/src/proto/vim9execute.pro
@@ -1,5 +1,6 @@
 /* vim9execute.c */
 void to_string_error(vartype_T vartype);
+void funcstack_check_refcount(funcstack_T *funcstack);
 int call_def_function(ufunc_T *ufunc, int argc_arg, typval_T *argv, partial_T *partial, typval_T *rettv);
 void ex_disassemble(exarg_T *eap);
 int tv2bool(typval_T *tv);