diff --git a/include/rtti/typeinfo.h b/include/rtti/typeinfo.h
index 527d9fc..4352a97 100644
--- a/include/rtti/typeinfo.h
+++ b/include/rtti/typeinfo.h
@@ -64,6 +64,7 @@ typedef struct typeinfo_ typeinfo_t;
 typedef size_t (*datasize_fn_t)(va_list);
 
 typedef void (*destroy_fn_t)(void*);
+typedef int (*comp_fn_t)(void*, void*, size_t);
 
 /* object life cycle */
 typedef int (*obj_init_fn_t)(meta_obj_t*, va_list);