diff --git a/src/proto/vim9class.pro b/src/proto/vim9class.pro
index 1b5800c..4c733d5 100644
--- a/src/proto/vim9class.pro
+++ b/src/proto/vim9class.pro
@@ -40,6 +40,7 @@
 void protected_method_access_errmsg(char_u *method_name);
 int object_empty(object_T *obj);
 int object_len(object_T *obj);
+int object_equal(object_T *o1, object_T *o2, int ic, int recursive);
 char_u *object2string(object_T *obj, char_u *numbuf, int copyID, int echo_style, int restore_copyID, int composite_val);
 int class_instance_of(class_T *cl, class_T *other_cl);
 void f_instanceof(typval_T *argvars, typval_T *rettv);