diff --git a/commit.h b/commit.h
index 7b1986d..884177b 100644
--- a/commit.h
+++ b/commit.h
@@ -263,8 +263,8 @@ extern struct commit_list *get_merge_bases_many_dirty(struct commit *one, int n,
 
 struct oid_array;
 struct ref;
-extern int register_shallow(const unsigned char *sha1);
-extern int unregister_shallow(const unsigned char *sha1);
+extern int register_shallow(const struct object_id *oid);
+extern int unregister_shallow(const struct object_id *oid);
 extern int for_each_commit_graft(each_commit_graft_fn, void *);
 extern int is_repository_shallow(void);
 extern struct commit_list *get_shallow_commits(struct object_array *heads,