diff --git a/src/proto/vim9class.pro b/src/proto/vim9class.pro
index e685c03..0f8aa7f 100644
--- a/src/proto/vim9class.pro
+++ b/src/proto/vim9class.pro
@@ -1,5 +1,5 @@
 /* vim9class.c */
-int object_index_from_itf_index(class_T *itf, int is_method, int idx, class_T *cl);
+int object_index_from_itf_index(class_T *itf, int is_method, int idx, class_T *cl, int is_static);
 void ex_class(exarg_T *eap);
 type_T *class_member_type(class_T *cl, int is_object, char_u *name, char_u *name_end, int *member_idx, ocmember_T **m);
 void ex_enum(exarg_T *eap);