1 files changed, 1 insertions, 0 deletions
diff --git a/internal.h b/internal.h
index 7a76ba2548..72892cb6cf 100644
--- a/internal.h
+++ b/internal.h
@@ -715,6 +715,7 @@ long rb_objid_hash(st_index_t index);
 VALUE rb_ident_hash_new(void);
 st_table *rb_init_identtable(void);
 st_table *rb_init_identtable_with_size(st_index_t size);
+VALUE rb_hash_compare_by_id_p(VALUE hash);
 
 #define RHASH_TBL_RAW(h) rb_hash_tbl_raw(h)
 VALUE rb_hash_keys(VALUE hash);