diff --git a/blob.c b/blob.c
index 342bdbb1bb..36f9abda19 100644
--- a/blob.c
+++ b/blob.c
@@ -7,10 +7,9 @@ const char *blob_type = "blob";
 
 struct blob *lookup_blob(struct repository *r, const struct object_id *oid)
 {
-	struct object *obj = lookup_object(r, oid->hash);
+	struct object *obj = lookup_object(r, oid);
 	if (!obj)
-		return create_object(r, oid->hash,
-				     alloc_blob_node(r));
+		return create_object(r, oid, alloc_blob_node(r));
 	return object_as_type(r, obj, OBJ_BLOB, 0);
 }
 
diff --git a/builtin/describe.c b/builtin/describe.c
index 1409cedce2..200154297d 100644
--- a/builtin/describe.c
+++ b/builtin/describe.c
@@ -76,7 +76,7 @@ static int commit_name_neq(const void *unused_cmp_data,
 
 static inline struct commit_name *find_commit_name(const struct object_id *peeled)
 {
-	return hashmap_get_from_hash(&names, sha1hash(peeled->hash), peeled->hash);
+	return hashmap_get_from_hash(&names, oidhash(peeled), peeled);
 }
 
 static int replace_name(struct commit_name *e,
@@ -123,7 +123,7 @@ static void add_to_known_names(const char *path,
 		if (!e) {
 			e = xmalloc(sizeof(struct commit_name));
 			oidcpy(&e->peeled, peeled);
-			hashmap_entry_init(e, sha1hash(peeled->hash));
+			hashmap_entry_init(e, oidhash(peeled));
 			hashmap_add(&names, e);
 			e->path = NULL;
 		}
diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index c22cef3b2f..f541f55d33 100644
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -275,7 +275,7 @@ static void export_blob(const struct object_id *oid)
 	if (is_null_oid(oid))
 		return;
 
-	object = lookup_object(the_repository, oid->hash);
+	object = lookup_object(the_repository, oid);
 	if (object && object->flags & SHOWN)
 		return;
 
@@ -453,7 +453,7 @@ static void show_filemodify(struct diff_queue_struct *q,
 						  &spec->oid));
 			else {
 				struct object *object = lookup_object(the_repository,
-								      spec->oid.hash);
+								      &spec->oid);
 				printf("M %06o :%d ", spec->mode,
 				       get_object_mark(object));
 			}
diff --git a/builtin/fsck.c b/builtin/fsck.c
index d26fb0a044..18403a94fa 100644
--- a/builtin/fsck.c
+++ b/builtin/fsck.c
@@ -238,7 +238,7 @@ static int mark_used(struct object *obj, int type, void *data, struct fsck_optio
 static void mark_unreachable_referents(const struct object_id *oid)
 {
 	struct fsck_options options = FSCK_OPTIONS_DEFAULT;
-	struct object *obj = lookup_object(the_repository, oid->hash);
+	struct object *obj = lookup_object(the_repository, oid);
 
 	if (!obj || !(obj->flags & HAS_OBJ))
 		return; /* not part of our original set */
@@ -497,7 +497,7 @@ static void fsck_handle_reflog_oid(const char *refname, struct object_id *oid,
 	struct object *obj;
 
 	if (!is_null_oid(oid)) {
-		obj = lookup_object(the_repository, oid->hash);
+		obj = lookup_object(the_repository, oid);
 		if (obj && (obj->flags & HAS_OBJ)) {
 			if (timestamp && name_objects)
 				add_decoration(fsck_walk_options.object_names,
@@ -756,7 +756,7 @@ static int fsck_cache_tree(struct cache_tree *it)
 
 static void mark_object_for_connectivity(const struct object_id *oid)
 {
-	struct object *obj = lookup_unknown_object(oid->hash);
+	struct object *obj = lookup_unknown_object(oid);
 	obj->flags |= HAS_OBJ;
 }
 
@@ -879,7 +879,7 @@ int cmd_fsck(int argc, const char **argv, const char *prefix)
 		struct object_id oid;
 		if (!get_oid(arg, &oid)) {
 			struct object *obj = lookup_object(the_repository,
-							   oid.hash);
+							   &oid);
 
 			if (!obj || !(obj->flags & HAS_OBJ)) {
 				if (is_promisor_object(&oid))
diff --git a/builtin/name-rev.c b/builtin/name-rev.c
index 16df43473a..c785fe16ba 100644
--- a/builtin/name-rev.c
+++ b/builtin/name-rev.c
@@ -378,8 +378,7 @@ static void name_rev_line(char *p, struct name_ref_data *data)
 			*(p+1) = 0;
 			if (!get_oid(p - (hexsz - 1), &oid)) {
 				struct object *o =
-					lookup_object(the_repository,
-						      oid.hash);
+					lookup_object(the_repository, &oid);
 				if (o)
 					name = get_rev_name(o, &buf);
 			}
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 698c901523..000dc4b872 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -606,12 +606,12 @@ static int mark_tagged(const char *path, const struct object_id *oid, int flag,
 		       void *cb_data)
 {
 	struct object_id peeled;
-	struct object_entry *entry = packlist_find(&to_pack, oid->hash, NULL);
+	struct object_entry *entry = packlist_find(&to_pack, oid, NULL);
 
 	if (entry)
 		entry->tagged = 1;
 	if (!peel_ref(path, &peeled)) {
-		entry = packlist_find(&to_pack, peeled.hash, NULL);
+		entry = packlist_find(&to_pack, &peeled, NULL);
 		if (entry)
 			entry->tagged = 1;
 	}
@@ -996,7 +996,7 @@ static int have_duplicate_entry(const struct object_id *oid,
 {
 	struct object_entry *entry;
 
-	entry = packlist_find(&to_pack, oid->hash, index_pos);
+	entry = packlist_find(&to_pack, oid, index_pos);
 	if (!entry)
 		return 0;
 
@@ -1494,11 +1494,13 @@ static int can_reuse_delta(const unsigned char *base_sha1,
 	if (!base_sha1)
 		return 0;
 
+	oidread(&base_oid, base_sha1);
+
 	/*
 	 * First see if we're already sending the base (or it's explicitly in
 	 * our "excluded" list).
 	 */
-	base = packlist_find(&to_pack, base_sha1, NULL);
+	base = packlist_find(&to_pack, &base_oid, NULL);
 	if (base) {
 		if (!in_same_island(&delta->idx.oid, &base->idx.oid))
 			return 0;
@@ -1511,7 +1513,6 @@ static int can_reuse_delta(const unsigned char *base_sha1,
 	 * even if it was buried too deep in history to make it into the
 	 * packing list.
 	 */
-	oidread(&base_oid, base_sha1);
 	if (thin && bitmap_has_oid_in_uninteresting(bitmap_git, &base_oid)) {
 		if (use_delta_islands) {
 			if (!in_same_island(&delta->idx.oid, &base_oid))
@@ -2571,7 +2572,7 @@ static void add_tag_chain(const struct object_id *oid)
 	 * it was included via bitmaps, we would not have parsed it
 	 * previously).
 	 */
-	if (packlist_find(&to_pack, oid->hash, NULL))
+	if (packlist_find(&to_pack, oid, NULL))
 		return;
 
 	tag = lookup_tag(the_repository, oid);
@@ -2595,7 +2596,7 @@ static int add_ref_tag(const char *path, const struct object_id *oid, int flag,
 
 	if (starts_with(path, "refs/tags/") && /* is a tag? */
 	    !peel_ref(path, &peeled)    && /* peelable? */
-	    packlist_find(&to_pack, peeled.hash, NULL))      /* object packed? */
+	    packlist_find(&to_pack, &peeled, NULL))      /* object packed? */
 		add_tag_chain(oid);
 	return 0;
 }
@@ -2795,7 +2796,7 @@ static void show_object(struct object *obj, const char *name, void *data)
 		for (p = strchr(name, '/'); p; p = strchr(p + 1, '/'))
 			depth++;
 
-		ent = packlist_find(&to_pack, obj->oid.hash, NULL);
+		ent = packlist_find(&to_pack, &obj->oid, NULL);
 		if (ent && depth > oe_tree_depth(&to_pack, ent))
 			oe_set_tree_depth(&to_pack, ent, depth);
 	}
@@ -2922,7 +2923,7 @@ static void add_objects_in_unpacked_packs(void)
 
 		for (i = 0; i < p->num_objects; i++) {
 			nth_packed_object_oid(&oid, p, i);
-			o = lookup_unknown_object(oid.hash);
+			o = lookup_unknown_object(&oid);
 			if (!(o->flags & OBJECT_ADDED))
 				mark_in_pack_object(o, p, &in_pack);
 			o->flags |= OBJECT_ADDED;
@@ -3026,7 +3027,7 @@ static void loosen_unused_packed_objects(void)
 
 		for (i = 0; i < p->num_objects; i++) {
 			nth_packed_object_oid(&oid, p, i);
-			if (!packlist_find(&to_pack, oid.hash, NULL) &&
+			if (!packlist_find(&to_pack, &oid, NULL) &&
 			    !has_sha1_pack_kept_or_nonlocal(&oid) &&
 			    !loosened_object_can_be_discarded(&oid, p->mtime))
 				if (force_object_loose(&oid, p->mtime))
diff --git a/builtin/prune.c b/builtin/prune.c
index 97613eccb5..2b76872ad2 100644
--- a/builtin/prune.c
+++ b/builtin/prune.c
@@ -53,7 +53,7 @@ static int is_object_reachable(const struct object_id *oid,
 
 	perform_reachability_traversal(revs);
 
-	obj = lookup_object(the_repository, oid->hash);
+	obj = lookup_object(the_repository, oid);
 	return obj && (obj->flags & SEEN);
 }
 
diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c
index 80478808b3..a87a4bfd2c 100644
--- a/builtin/unpack-objects.c
+++ b/builtin/unpack-objects.c
@@ -332,7 +332,7 @@ static int resolve_against_held(unsigned nr, const struct object_id *base,
 {
 	struct object *obj;
 	struct obj_buffer *obj_buffer;
-	obj = lookup_object(the_repository, base->hash);
+	obj = lookup_object(the_repository, base);
 	if (!obj)
 		return 0;
 	obj_buffer = lookup_object_buffer(obj);
diff --git a/cache.h b/cache.h
index bf20337ef4..37e0b82064 100644
--- a/cache.h
+++ b/cache.h
@@ -43,30 +43,6 @@ int git_deflate_end_gently(git_zstream *);
 int git_deflate(git_zstream *, int flush);
 unsigned long git_deflate_bound(git_zstream *, unsigned long);
 
-/* The length in bytes and in hex digits of an object name (SHA-1 value). */
-#define GIT_SHA1_RAWSZ 20
-#define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ)
-/* The block size of SHA-1. */
-#define GIT_SHA1_BLKSZ 64
-
-/* The length in bytes and in hex digits of an object name (SHA-256 value). */
-#define GIT_SHA256_RAWSZ 32
-#define GIT_SHA256_HEXSZ (2 * GIT_SHA256_RAWSZ)
-/* The block size of SHA-256. */
-#define GIT_SHA256_BLKSZ 64
-
-/* The length in byte and in hex digits of the largest possible hash value. */
-#define GIT_MAX_RAWSZ GIT_SHA256_RAWSZ
-#define GIT_MAX_HEXSZ GIT_SHA256_HEXSZ
-/* The largest possible block size for any supported hash. */
-#define GIT_MAX_BLKSZ GIT_SHA256_BLKSZ
-
-struct object_id {
-	unsigned char hash[GIT_MAX_RAWSZ];
-};
-
-#define the_hash_algo the_repository->hash_algo
-
 #if defined(DT_UNKNOWN) && !defined(NO_D_TYPE_IN_DIRENT)
 #define DTYPE(de)	((de)->d_type)
 #else
diff --git a/commit-graph.c b/commit-graph.c
index 1752341098..8cc1d1d6c3 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -1279,7 +1279,7 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g)
 		hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
 
 		graph_commit = lookup_commit(r, &cur_oid);
-		odb_commit = (struct commit *)create_object(r, cur_oid.hash, alloc_commit_node(r));
+		odb_commit = (struct commit *)create_object(r, &cur_oid, alloc_commit_node(r));
 		if (parse_commit_internal(odb_commit, 0, 0)) {
 			graph_report(_("failed to parse commit %s from object database for commit-graph"),
 				     oid_to_hex(&cur_oid));
diff --git a/commit.c b/commit.c
index 26ce0770f6..a98de16e3d 100644
--- a/commit.c
+++ b/commit.c
@@ -57,10 +57,9 @@ struct commit *lookup_commit_or_die(const struct object_id *oid, const char *ref
 
 struct commit *lookup_commit(struct repository *r, const struct object_id *oid)
 {
-	struct object *obj = lookup_object(r, oid->hash);
+	struct object *obj = lookup_object(r, oid);
 	if (!obj)
-		return create_object(r, oid->hash,
-				     alloc_commit_node(r));
+		return create_object(r, oid, alloc_commit_node(r));
 	return object_as_type(r, obj, OBJ_COMMIT, 0);
 }
 
diff --git a/decorate.c b/decorate.c
index de31331fa4..a605b1b5f4 100644
--- a/decorate.c
+++ b/decorate.c
@@ -8,7 +8,7 @@
 
 static unsigned int hash_obj(const struct object *obj, unsigned int n)
 {
-	return sha1hash(obj->oid.hash) % n;
+	return oidhash(&obj->oid) % n;
 }
 
 static void *insert_decoration(struct decoration *n, const struct object *base, void *decoration)
diff --git a/delta-islands.c b/delta-islands.c
index b959f6c380..09dbd3cf72 100644
--- a/delta-islands.c
+++ b/delta-islands.c
@@ -22,7 +22,7 @@
 
 KHASH_INIT(str, const char *, void *, 1, kh_str_hash_func, kh_str_hash_equal)
 
-static khash_sha1 *island_marks;
+static kh_oid_map_t *island_marks;
 static unsigned island_counter;
 static unsigned island_counter_core;
 
@@ -105,7 +105,7 @@ int in_same_island(const struct object_id *trg_oid, const struct object_id *src_
 	 * If we don't have a bitmap for the target, we can delta it
 	 * against anything -- it's not an important object
 	 */
-	trg_pos = kh_get_sha1(island_marks, trg_oid->hash);
+	trg_pos = kh_get_oid_map(island_marks, *trg_oid);
 	if (trg_pos >= kh_end(island_marks))
 		return 1;
 
@@ -113,7 +113,7 @@ int in_same_island(const struct object_id *trg_oid, const struct object_id *src_
 	 * if the source (our delta base) doesn't have a bitmap,
 	 * we don't want to base any deltas on it!
 	 */
-	src_pos = kh_get_sha1(island_marks, src_oid->hash);
+	src_pos = kh_get_oid_map(island_marks, *src_oid);
 	if (src_pos >= kh_end(island_marks))
 		return 0;
 
@@ -129,11 +129,11 @@ int island_delta_cmp(const struct object_id *a, const struct object_id *b)
 	if (!island_marks)
 		return 0;
 
-	a_pos = kh_get_sha1(island_marks, a->hash);
+	a_pos = kh_get_oid_map(island_marks, *a);
 	if (a_pos < kh_end(island_marks))
 		a_bitmap = kh_value(island_marks, a_pos);
 
-	b_pos = kh_get_sha1(island_marks, b->hash);
+	b_pos = kh_get_oid_map(island_marks, *b);
 	if (b_pos < kh_end(island_marks))
 		b_bitmap = kh_value(island_marks, b_pos);
 
@@ -154,7 +154,7 @@ static struct island_bitmap *create_or_get_island_marks(struct object *obj)
 	khiter_t pos;
 	int hash_ret;
 
-	pos = kh_put_sha1(island_marks, obj->oid.hash, &hash_ret);
+	pos = kh_put_oid_map(island_marks, obj->oid, &hash_ret);
 	if (hash_ret)
 		kh_value(island_marks, pos) = island_bitmap_new(NULL);
 
@@ -167,7 +167,7 @@ static void set_island_marks(struct object *obj, struct island_bitmap *marks)
 	khiter_t pos;
 	int hash_ret;
 
-	pos = kh_put_sha1(island_marks, obj->oid.hash, &hash_ret);
+	pos = kh_put_oid_map(island_marks, obj->oid, &hash_ret);
 	if (hash_ret) {
 		/*
 		 * We don't have one yet; make a copy-on-write of the
@@ -279,7 +279,7 @@ void resolve_tree_islands(struct repository *r,
 		struct name_entry entry;
 		khiter_t pos;
 
-		pos = kh_get_sha1(island_marks, ent->idx.oid.hash);
+		pos = kh_get_oid_map(island_marks, ent->idx.oid);
 		if (pos >= kh_end(island_marks))
 			continue;
 
@@ -296,7 +296,7 @@ void resolve_tree_islands(struct repository *r,
 			if (S_ISGITLINK(entry.mode))
 				continue;
 
-			obj = lookup_object(r, entry.oid.hash);
+			obj = lookup_object(r, &entry.oid);
 			if (!obj)
 				continue;
 
@@ -456,7 +456,7 @@ static void deduplicate_islands(struct repository *r)
 
 void load_delta_islands(struct repository *r, int progress)
 {
-	island_marks = kh_init_sha1();
+	island_marks = kh_init_oid_map();
 	remote_islands = kh_init_str();
 
 	git_config(island_config_callback, NULL);
@@ -469,7 +469,7 @@ void load_delta_islands(struct repository *r, int progress)
 
 void propagate_island_marks(struct commit *commit)
 {
-	khiter_t pos = kh_get_sha1(island_marks, commit->object.oid.hash);
+	khiter_t pos = kh_get_oid_map(island_marks, commit->object.oid);
 
 	if (pos < kh_end(island_marks)) {
 		struct commit_list *p;
@@ -491,7 +491,7 @@ int compute_pack_layers(struct packing_data *to_pack)
 
 	for (i = 0; i < to_pack->nr_objects; ++i) {
 		struct object_entry *entry = &to_pack->objects[i];
-		khiter_t pos = kh_get_sha1(island_marks, entry->idx.oid.hash);
+		khiter_t pos = kh_get_oid_map(island_marks, entry->idx.oid);
 
 		oe_set_layer(to_pack, entry, 1);
 
diff --git a/diffcore-rename.c b/diffcore-rename.c
index 6af92d5eba..9624864858 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -266,7 +266,7 @@ static unsigned int hash_filespec(struct repository *r,
 		hash_object_file(filespec->data, filespec->size, "blob",
 				 &filespec->oid);
 	}
-	return sha1hash(filespec->oid.hash);
+	return oidhash(&filespec->oid);
 }
 
 static int find_identical_files(struct hashmap *srcs,
diff --git a/fetch-pack.c b/fetch-pack.c
index 1c10f54e78..07bc48a1a5 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -286,7 +286,7 @@ static int find_common(struct fetch_negotiator *negotiator,
 		 * we cannot trust the object flags).
 		 */
 		if (!args->no_dependents &&
-		    ((o = lookup_object(the_repository, remote->hash)) != NULL) &&
+		    ((o = lookup_object(the_repository, remote)) != NULL) &&
 				(o->flags & COMPLETE)) {
 			continue;
 		}
@@ -364,7 +364,7 @@ static int find_common(struct fetch_negotiator *negotiator,
 			if (skip_prefix(reader.line, "unshallow ", &arg)) {
 				if (get_oid_hex(arg, &oid))
 					die(_("invalid unshallow line: %s"), reader.line);
-				if (!lookup_object(the_repository, oid.hash))
+				if (!lookup_object(the_repository, &oid))
 					die(_("object not found: %s"), reader.line);
 				/* make sure that it is parsed as shallow */
 				if (!parse_object(the_repository, &oid))
@@ -707,7 +707,7 @@ static void mark_complete_and_common_ref(struct fetch_negotiator *negotiator,
 	for (ref = *refs; ref; ref = ref->next) {
 		struct object *o = deref_tag(the_repository,
 					     lookup_object(the_repository,
-					     ref->old_oid.hash),
+					     &ref->old_oid),
 					     NULL, 0);
 
 		if (!o || o->type != OBJ_COMMIT || !(o->flags & COMPLETE))
@@ -734,7 +734,7 @@ static int everything_local(struct fetch_pack_args *args,
 		const struct object_id *remote = &ref->old_oid;
 		struct object *o;
 
-		o = lookup_object(the_repository, remote->hash);
+		o = lookup_object(the_repository, remote);
 		if (!o || !(o->flags & COMPLETE)) {
 			retval = 0;
 			print_verbose(args, "want %s (%s)", oid_to_hex(remote),
@@ -1048,7 +1048,7 @@ static void add_wants(int no_dependents, const struct ref *wants, struct strbuf
 		 * we cannot trust the object flags).
 		 */
 		if (!no_dependents &&
-		    ((o = lookup_object(the_repository, remote->hash)) != NULL) &&
+		    ((o = lookup_object(the_repository, remote)) != NULL) &&
 		    (o->flags & COMPLETE)) {
 			continue;
 		}
@@ -1275,7 +1275,7 @@ static void receive_shallow_info(struct fetch_pack_args *args,
 		if (skip_prefix(reader->line, "unshallow ", &arg)) {
 			if (get_oid_hex(arg, &oid))
 				die(_("invalid unshallow line: %s"), reader->line);
-			if (!lookup_object(the_repository, oid.hash))
+			if (!lookup_object(the_repository, &oid))
 				die(_("object not found: %s"), reader->line);
 			/* make sure that it is parsed as shallow */
 			if (!parse_object(the_repository, &oid))
diff --git a/fsck.c b/fsck.c
index 4703f55561..117c4a978f 100644
--- a/fsck.c
+++ b/fsck.c
@@ -1092,7 +1092,7 @@ int fsck_finish(struct fsck_options *options)
 
 		blob = lookup_blob(the_repository, oid);
 		if (!blob) {
-			struct object *obj = lookup_unknown_object(oid->hash);
+			struct object *obj = lookup_unknown_object(oid);
 			ret |= report(options, obj,
 				      FSCK_MSG_GITMODULES_BLOB,
 				      "non-blob found at .gitmodules");
diff --git a/hash.h b/hash.h
index 661c9f2281..52a4f1a3f4 100644
--- a/hash.h
+++ b/hash.h
@@ -139,4 +139,28 @@ static inline int hash_algo_by_ptr(const struct git_hash_algo *p)
 	return p - hash_algos;
 }
 
+/* The length in bytes and in hex digits of an object name (SHA-1 value). */
+#define GIT_SHA1_RAWSZ 20
+#define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ)
+/* The block size of SHA-1. */
+#define GIT_SHA1_BLKSZ 64
+
+/* The length in bytes and in hex digits of an object name (SHA-256 value). */
+#define GIT_SHA256_RAWSZ 32
+#define GIT_SHA256_HEXSZ (2 * GIT_SHA256_RAWSZ)
+/* The block size of SHA-256. */
+#define GIT_SHA256_BLKSZ 64
+
+/* The length in byte and in hex digits of the largest possible hash value. */
+#define GIT_MAX_RAWSZ GIT_SHA256_RAWSZ
+#define GIT_MAX_HEXSZ GIT_SHA256_HEXSZ
+/* The largest possible block size for any supported hash. */
+#define GIT_MAX_BLKSZ GIT_SHA256_BLKSZ
+
+struct object_id {
+	unsigned char hash[GIT_MAX_RAWSZ];
+};
+
+#define the_hash_algo the_repository->hash_algo
+
 #endif
diff --git a/hashmap.h b/hashmap.h
index f95593b6cf..8424911566 100644
--- a/hashmap.h
+++ b/hashmap.h
@@ -1,6 +1,8 @@
 #ifndef HASHMAP_H
 #define HASHMAP_H
 
+#include "hash.h"
+
 /*
  * Generic implementation of hash-based key-value mappings.
  *
@@ -118,14 +120,14 @@ unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len);
  * the results will be different on big-endian and little-endian
  * platforms, so they should not be stored or transferred over the net.
  */
-static inline unsigned int sha1hash(const unsigned char *sha1)
+static inline unsigned int oidhash(const struct object_id *oid)
 {
 	/*
-	 * Equivalent to 'return *(unsigned int *)sha1;', but safe on
+	 * Equivalent to 'return *(unsigned int *)oid->hash;', but safe on
 	 * platforms that don't support unaligned reads.
 	 */
 	unsigned int hash;
-	memcpy(&hash, sha1, sizeof(hash));
+	memcpy(&hash, oid->hash, sizeof(hash));
 	return hash;
 }
 
diff --git a/http-push.c b/http-push.c
index e36561a6db..0353f9f514 100644
--- a/http-push.c
+++ b/http-push.c
@@ -723,7 +723,7 @@ static void one_remote_object(const struct object_id *oid)
 {
 	struct object *obj;
 
-	obj = lookup_object(the_repository, oid->hash);
+	obj = lookup_object(the_repository, oid);
 	if (!obj)
 		obj = parse_object(the_repository, oid);
 
@@ -1432,7 +1432,7 @@ static void one_remote_ref(const char *refname)
 	 * may be required for updating server info later.
 	 */
 	if (repo->can_update_info_refs && !has_object_file(&ref->old_oid)) {
-		obj = lookup_unknown_object(ref->old_oid.hash);
+		obj = lookup_unknown_object(&ref->old_oid);
 		fprintf(stderr,	"  fetch %s for %s\n",
 			oid_to_hex(&ref->old_oid), refname);
 		add_fetch_request(obj);
diff --git a/khash.h b/khash.h
index af747a683f..21c2095216 100644
--- a/khash.h
+++ b/khash.h
@@ -324,30 +324,20 @@ static const double __ac_HASH_UPPER = 0.77;
 		code;												\
 	} }
 
-#define __kh_oid_cmp(a, b) (hashcmp(a, b) == 0)
-
-KHASH_INIT(sha1, const unsigned char *, void *, 1, sha1hash, __kh_oid_cmp)
-typedef kh_sha1_t khash_sha1;
-
-KHASH_INIT(sha1_pos, const unsigned char *, int, 1, sha1hash, __kh_oid_cmp)
-typedef kh_sha1_pos_t khash_sha1_pos;
-
-static inline unsigned int oid_hash(struct object_id oid)
+static inline unsigned int oidhash_by_value(struct object_id oid)
 {
-	return sha1hash(oid.hash);
+	return oidhash(&oid);
 }
 
-static inline int oid_equal(struct object_id a, struct object_id b)
+static inline int oideq_by_value(struct object_id a, struct object_id b)
 {
 	return oideq(&a, &b);
 }
 
-KHASH_INIT(oid, struct object_id, int, 0, oid_hash, oid_equal)
+KHASH_INIT(oid_set, struct object_id, int, 0, oidhash_by_value, oideq_by_value)
 
-KHASH_INIT(oid_map, struct object_id, void *, 1, oid_hash, oid_equal)
-typedef kh_oid_t khash_oid_map;
+KHASH_INIT(oid_map, struct object_id, void *, 1, oidhash_by_value, oideq_by_value)
 
-KHASH_INIT(oid_pos, struct object_id, int, 1, oid_hash, oid_equal)
-typedef kh_oid_pos_t khash_oid_pos;
+KHASH_INIT(oid_pos, struct object_id, int, 1, oidhash_by_value, oideq_by_value)
 
 #endif /* __AC_KHASH_H */
diff --git a/object.c b/object.c
index cf1a2b7086..07bdd5b26e 100644
--- a/object.c
+++ b/object.c
@@ -59,9 +59,9 @@ int type_from_string_gently(const char *str, ssize_t len, int gentle)
  * the specified sha1.  n must be a power of 2.  Please note that the
  * return value is *not* consistent across computer architectures.
  */
-static unsigned int hash_obj(const unsigned char *sha1, unsigned int n)
+static unsigned int hash_obj(const struct object_id *oid, unsigned int n)
 {
-	return sha1hash(sha1) & (n - 1);
+	return oidhash(oid) & (n - 1);
 }
 
 /*
@@ -71,7 +71,7 @@ static unsigned int hash_obj(const unsigned char *sha1, unsigned int n)
  */
 static void insert_obj_hash(struct object *obj, struct object **hash, unsigned int size)
 {
-	unsigned int j = hash_obj(obj->oid.hash, size);
+	unsigned int j = hash_obj(&obj->oid, size);
 
 	while (hash[j]) {
 		j++;
@@ -85,7 +85,7 @@ static void insert_obj_hash(struct object *obj, struct object **hash, unsigned i
  * Look up the record for the given sha1 in the hash map stored in
  * obj_hash.  Return NULL if it was not found.
  */
-struct object *lookup_object(struct repository *r, const unsigned char *sha1)
+struct object *lookup_object(struct repository *r, const struct object_id *oid)
 {
 	unsigned int i, first;
 	struct object *obj;
@@ -93,9 +93,9 @@ struct object *lookup_object(struct repository *r, const unsigned char *sha1)
 	if (!r->parsed_objects->obj_hash)
 		return NULL;
 
-	first = i = hash_obj(sha1, r->parsed_objects->obj_hash_size);
+	first = i = hash_obj(oid, r->parsed_objects->obj_hash_size);
 	while ((obj = r->parsed_objects->obj_hash[i]) != NULL) {
-		if (hasheq(sha1, obj->oid.hash))
+		if (oideq(oid, &obj->oid))
 			break;
 		i++;
 		if (i == r->parsed_objects->obj_hash_size)
@@ -141,13 +141,13 @@ static void grow_object_hash(struct repository *r)
 	r->parsed_objects->obj_hash_size = new_hash_size;
 }
 
-void *create_object(struct repository *r, const unsigned char *sha1, void *o)
+void *create_object(struct repository *r, const struct object_id *oid, void *o)
 {
 	struct object *obj = o;
 
 	obj->parsed = 0;
 	obj->flags = 0;
-	hashcpy(obj->oid.hash, sha1);
+	oidcpy(&obj->oid, oid);
 
 	if (r->parsed_objects->obj_hash_size - 1 <= r->parsed_objects->nr_objs * 2)
 		grow_object_hash(r);
@@ -178,11 +178,11 @@ void *object_as_type(struct repository *r, struct object *obj, enum object_type
 	}
 }
 
-struct object *lookup_unknown_object(const unsigned char *sha1)
+struct object *lookup_unknown_object(const struct object_id *oid)
 {
-	struct object *obj = lookup_object(the_repository, sha1);
+	struct object *obj = lookup_object(the_repository, oid);
 	if (!obj)
-		obj = create_object(the_repository, sha1,
+		obj = create_object(the_repository, oid,
 				    alloc_object_node(the_repository));
 	return obj;
 }
@@ -256,7 +256,7 @@ struct object *parse_object(struct repository *r, const struct object_id *oid)
 	void *buffer;
 	struct object *obj;
 
-	obj = lookup_object(r, oid->hash);
+	obj = lookup_object(r, oid);
 	if (obj && obj->parsed)
 		return obj;
 
@@ -268,7 +268,7 @@ struct object *parse_object(struct repository *r, const struct object_id *oid)
 			return NULL;
 		}
 		parse_blob_buffer(lookup_blob(r, oid), NULL, 0);
-		return lookup_object(r, oid->hash);
+		return lookup_object(r, oid);
 	}
 
 	buffer = repo_read_object_file(r, oid, &type, &size);
diff --git a/object.h b/object.h
index 4526979ccf..0120892bbd 100644
--- a/object.h
+++ b/object.h
@@ -116,9 +116,9 @@ struct object *get_indexed_object(unsigned int);
  * half-initialised objects, the caller is expected to initialize them
  * by calling parse_object() on them.
  */
-struct object *lookup_object(struct repository *r, const unsigned char *sha1);
+struct object *lookup_object(struct repository *r, const struct object_id *oid);
 
-void *create_object(struct repository *r, const unsigned char *sha1, void *obj);
+void *create_object(struct repository *r, const struct object_id *oid, void *obj);
 
 void *object_as_type(struct repository *r, struct object *obj, enum object_type type, int quiet);
 
@@ -143,7 +143,7 @@ struct object *parse_object_or_die(const struct object_id *oid, const char *name
 struct object *parse_object_buffer(struct repository *r, const struct object_id *oid, enum object_type type, unsigned long size, void *buffer, int *eaten_p);
 
 /** Returns the object, with potentially excess memory allocated. **/
-struct object *lookup_unknown_object(const unsigned  char *sha1);
+struct object *lookup_unknown_object(const struct object_id *oid);
 
 struct object_list *object_list_insert(struct object *item,
 				       struct object_list **list_p);
diff --git a/oidset.c b/oidset.c
index fe4eb921df..8bdecb13de 100644
--- a/oidset.c
+++ b/oidset.c
@@ -5,33 +5,33 @@ void oidset_init(struct oidset *set, size_t initial_size)
 {
 	memset(&set->set, 0, sizeof(set->set));
 	if (initial_size)
-		kh_resize_oid(&set->set, initial_size);
+		kh_resize_oid_set(&set->set, initial_size);
 }
 
 int oidset_contains(const struct oidset *set, const struct object_id *oid)
 {
-	khiter_t pos = kh_get_oid(&set->set, *oid);
+	khiter_t pos = kh_get_oid_set(&set->set, *oid);
 	return pos != kh_end(&set->set);
 }
 
 int oidset_insert(struct oidset *set, const struct object_id *oid)
 {
 	int added;
-	kh_put_oid(&set->set, *oid, &added);
+	kh_put_oid_set(&set->set, *oid, &added);
 	return !added;
 }
 
 int oidset_remove(struct oidset *set, const struct object_id *oid)
 {
-	khiter_t pos = kh_get_oid(&set->set, *oid);
+	khiter_t pos = kh_get_oid_set(&set->set, *oid);
 	if (pos == kh_end(&set->set))
 		return 0;
-	kh_del_oid(&set->set, pos);
+	kh_del_oid_set(&set->set, pos);
 	return 1;
 }
 
 void oidset_clear(struct oidset *set)
 {
-	kh_release_oid(&set->set);
+	kh_release_oid_set(&set->set);
 	oidset_init(set, 0);
 }
diff --git a/oidset.h b/oidset.h
index 14f18f791f..505fad578b 100644
--- a/oidset.h
+++ b/oidset.h
@@ -20,7 +20,7 @@
  * A single oidset; should be zero-initialized (or use OIDSET_INIT).
  */
 struct oidset {
-	kh_oid_t set;
+	kh_oid_set_t set;
 };
 
 #define OIDSET_INIT { { 0 } }
@@ -62,7 +62,7 @@ int oidset_remove(struct oidset *set, const struct object_id *oid);
 void oidset_clear(struct oidset *set);
 
 struct oidset_iter {
-	kh_oid_t *set;
+	kh_oid_set_t *set;
 	khiter_t iter;
 };
 
diff --git a/pack-bitmap-write.c b/pack-bitmap-write.c
index 802ed62677..fa78a460c9 100644
--- a/pack-bitmap-write.c
+++ b/pack-bitmap-write.c
@@ -28,8 +28,8 @@ struct bitmap_writer {
 	struct ewah_bitmap *blobs;
 	struct ewah_bitmap *tags;
 
-	khash_sha1 *bitmaps;
-	khash_sha1 *reused;
+	kh_oid_map_t *bitmaps;
+	kh_oid_map_t *reused;
 	struct packing_data *to_pack;
 
 	struct bitmapped_commit *selected;
@@ -142,13 +142,13 @@ static inline void reset_all_seen(void)
 	seen_objects_nr = 0;
 }
 
-static uint32_t find_object_pos(const unsigned char *hash)
+static uint32_t find_object_pos(const struct object_id *oid)
 {
-	struct object_entry *entry = packlist_find(writer.to_pack, hash, NULL);
+	struct object_entry *entry = packlist_find(writer.to_pack, oid, NULL);
 
 	if (!entry) {
 		die("Failed to write bitmap index. Packfile doesn't have full closure "
-			"(object %s is missing)", hash_to_hex(hash));
+			"(object %s is missing)", oid_to_hex(oid));
 	}
 
 	return oe_in_pack_pos(writer.to_pack, entry);
@@ -157,7 +157,7 @@ static uint32_t find_object_pos(const unsigned char *hash)
 static void show_object(struct object *object, const char *name, void *data)
 {
 	struct bitmap *base = data;
-	bitmap_set(base, find_object_pos(object->oid.hash));
+	bitmap_set(base, find_object_pos(&object->oid));
 	mark_as_seen(object);
 }
 
@@ -170,12 +170,12 @@ static int
 add_to_include_set(struct bitmap *base, struct commit *commit)
 {
 	khiter_t hash_pos;
-	uint32_t bitmap_pos = find_object_pos(commit->object.oid.hash);
+	uint32_t bitmap_pos = find_object_pos(&commit->object.oid);
 
 	if (bitmap_get(base, bitmap_pos))
 		return 0;
 
-	hash_pos = kh_get_sha1(writer.bitmaps, commit->object.oid.hash);
+	hash_pos = kh_get_oid_map(writer.bitmaps, commit->object.oid);
 	if (hash_pos < kh_end(writer.bitmaps)) {
 		struct bitmapped_commit *bc = kh_value(writer.bitmaps, hash_pos);
 		bitmap_or_ewah(base, bc->bitmap);
@@ -256,7 +256,7 @@ void bitmap_writer_build(struct packing_data *to_pack)
 	struct bitmap *base = bitmap_new();
 	struct rev_info revs;
 
-	writer.bitmaps = kh_init_sha1();
+	writer.bitmaps = kh_init_oid_map();
 	writer.to_pack = to_pack;
 
 	if (writer.show_progress)
@@ -311,7 +311,7 @@ void bitmap_writer_build(struct packing_data *to_pack)
 		if (i >= reuse_after)
 			stored->flags |= BITMAP_FLAG_REUSE;
 
-		hash_pos = kh_put_sha1(writer.bitmaps, object->oid.hash, &hash_ret);
+		hash_pos = kh_put_oid_map(writer.bitmaps, object->oid, &hash_ret);
 		if (hash_ret == 0)
 			die("Duplicate entry when writing index: %s",
 			    oid_to_hex(&object->oid));
@@ -366,7 +366,7 @@ void bitmap_writer_reuse_bitmaps(struct packing_data *to_pack)
 	if (!(bitmap_git = prepare_bitmap_git(to_pack->repo)))
 		return;
 
-	writer.reused = kh_init_sha1();
+	writer.reused = kh_init_oid_map();
 	rebuild_existing_bitmaps(bitmap_git, to_pack, writer.reused,
 				 writer.show_progress);
 	/*
@@ -375,14 +375,14 @@ void bitmap_writer_reuse_bitmaps(struct packing_data *to_pack)
 	 */
 }
 
-static struct ewah_bitmap *find_reused_bitmap(const unsigned char *sha1)
+static struct ewah_bitmap *find_reused_bitmap(const struct object_id *oid)
 {
 	khiter_t hash_pos;
 
 	if (!writer.reused)
 		return NULL;
 
-	hash_pos = kh_get_sha1(writer.reused, sha1);
+	hash_pos = kh_get_oid_map(writer.reused, *oid);
 	if (hash_pos >= kh_end(writer.reused))
 		return NULL;
 
@@ -422,14 +422,14 @@ void bitmap_writer_select_commits(struct commit **indexed_commits,
 
 		if (next == 0) {
 			chosen = indexed_commits[i];
-			reused_bitmap = find_reused_bitmap(chosen->object.oid.hash);
+			reused_bitmap = find_reused_bitmap(&chosen->object.oid);
 		} else {
 			chosen = indexed_commits[i + next];
 
 			for (j = 0; j <= next; ++j) {
 				struct commit *cm = indexed_commits[i + j];
 
-				reused_bitmap = find_reused_bitmap(cm->object.oid.hash);
+				reused_bitmap = find_reused_bitmap(&cm->object.oid);
 				if (reused_bitmap || (cm->object.flags & NEEDS_BITMAP) != 0) {
 					chosen = cm;
 					break;
diff --git a/pack-bitmap.c b/pack-bitmap.c
index 6069b2fe55..ed2befaac6 100644
--- a/pack-bitmap.c
+++ b/pack-bitmap.c
@@ -365,7 +365,7 @@ struct include_data {
 static inline int bitmap_position_extended(struct bitmap_index *bitmap_git,
 					   const struct object_id *oid)
 {
-	khash_oid_pos *positions = bitmap_git->ext_index.positions;
+	kh_oid_pos_t *positions = bitmap_git->ext_index.positions;
 	khiter_t pos = kh_get_oid_pos(positions, *oid);
 
 	if (pos < kh_end(positions)) {
@@ -1041,7 +1041,7 @@ static int rebuild_bitmap(uint32_t *reposition,
 
 int rebuild_existing_bitmaps(struct bitmap_index *bitmap_git,
 			     struct packing_data *mapping,
-			     khash_sha1 *reused_bitmaps,
+			     kh_oid_map_t *reused_bitmaps,
 			     int show_progress)
 {
 	uint32_t i, num_objects;
@@ -1057,13 +1057,13 @@ int rebuild_existing_bitmaps(struct bitmap_index *bitmap_git,
 	reposition = xcalloc(num_objects, sizeof(uint32_t));
 
 	for (i = 0; i < num_objects; ++i) {
-		const unsigned char *sha1;
+		struct object_id oid;
 		struct revindex_entry *entry;
 		struct object_entry *oe;
 
 		entry = &bitmap_git->pack->revindex[i];
-		sha1 = nth_packed_object_sha1(bitmap_git->pack, entry->nr);
-		oe = packlist_find(mapping, sha1, NULL);
+		nth_packed_object_oid(&oid, bitmap_git->pack, entry->nr);
+		oe = packlist_find(mapping, &oid, NULL);
 
 		if (oe)
 			reposition[i] = oe_in_pack_pos(mapping, oe) + 1;
@@ -1080,9 +1080,9 @@ int rebuild_existing_bitmaps(struct bitmap_index *bitmap_git,
 			if (!rebuild_bitmap(reposition,
 					    lookup_stored_bitmap(stored),
 					    rebuild)) {
-				hash_pos = kh_put_sha1(reused_bitmaps,
-						       stored->oid.hash,
-						       &hash_ret);
+				hash_pos = kh_put_oid_map(reused_bitmaps,
+							  stored->oid,
+							  &hash_ret);
 				kh_value(reused_bitmaps, hash_pos) =
 					bitmap_to_ewah(rebuild);
 			}
diff --git a/pack-bitmap.h b/pack-bitmap.h
index ee9792264c..00de3ec8e4 100644
--- a/pack-bitmap.h
+++ b/pack-bitmap.h
@@ -51,7 +51,7 @@ int reuse_partial_packfile_from_bitmap(struct bitmap_index *,
 				       struct packed_git **packfile,
 				       uint32_t *entries, off_t *up_to);
 int rebuild_existing_bitmaps(struct bitmap_index *, struct packing_data *mapping,
-			     khash_sha1 *reused_bitmaps, int show_progress);
+			     kh_oid_map_t *reused_bitmaps, int show_progress);
 void free_bitmap_index(struct bitmap_index *);
 
 /*
diff --git a/pack-objects.c b/pack-objects.c
index ce33b8906e..52560293b6 100644
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -6,17 +6,17 @@
 #include "config.h"
 
 static uint32_t locate_object_entry_hash(struct packing_data *pdata,
-					 const unsigned char *sha1,
+					 const struct object_id *oid,
 					 int *found)
 {
 	uint32_t i, mask = (pdata->index_size - 1);
 
-	i = sha1hash(sha1) & mask;
+	i = oidhash(oid) & mask;
 
 	while (pdata->index[i] > 0) {
 		uint32_t pos = pdata->index[i] - 1;
 
-		if (hasheq(sha1, pdata->objects[pos].idx.oid.hash)) {
+		if (oideq(oid, &pdata->objects[pos].idx.oid)) {
 			*found = 1;
 			return i;
 		}
@@ -56,7 +56,7 @@ static void rehash_objects(struct packing_data *pdata)
 	for (i = 0; i < pdata->nr_objects; i++) {
 		int found;
 		uint32_t ix = locate_object_entry_hash(pdata,
-						       entry->idx.oid.hash,
+						       &entry->idx.oid,
 						       &found);
 
 		if (found)
@@ -68,7 +68,7 @@ static void rehash_objects(struct packing_data *pdata)
 }
 
 struct object_entry *packlist_find(struct packing_data *pdata,
-				   const unsigned char *sha1,
+				   const struct object_id *oid,
 				   uint32_t *index_pos)
 {
 	uint32_t i;
@@ -77,7 +77,7 @@ struct object_entry *packlist_find(struct packing_data *pdata,
 	if (!pdata->index_size)
 		return NULL;
 
-	i = locate_object_entry_hash(pdata, sha1, &found);
+	i = locate_object_entry_hash(pdata, oid, &found);
 
 	if (index_pos)
 		*index_pos = i;
diff --git a/pack-objects.h b/pack-objects.h
index 6fde7ce27c..857d43850b 100644
--- a/pack-objects.h
+++ b/pack-objects.h
@@ -187,7 +187,7 @@ struct object_entry *packlist_alloc(struct packing_data *pdata,
 				    uint32_t index_pos);
 
 struct object_entry *packlist_find(struct packing_data *pdata,
-				   const unsigned char *sha1,
+				   const struct object_id *oid,
 				   uint32_t *index_pos);
 
 static inline uint32_t pack_name_hash(const char *name)
diff --git a/patch-ids.c b/patch-ids.c
index f70d396654..e8c150d0c9 100644
--- a/patch-ids.c
+++ b/patch-ids.c
@@ -83,7 +83,7 @@ static int init_patch_id_entry(struct patch_id *patch,
 	if (commit_patch_id(commit, &ids->diffopts, &header_only_patch_id, 1, 0))
 		return -1;
 
-	hashmap_entry_init(patch, sha1hash(header_only_patch_id.hash));
+	hashmap_entry_init(patch, oidhash(&header_only_patch_id));
 	return 0;
 }
 
diff --git a/reachable.c b/reachable.c
index 0d00a91de4..8f50235b28 100644
--- a/reachable.c
+++ b/reachable.c
@@ -109,7 +109,7 @@ static int add_recent_loose(const struct object_id *oid,
 			    const char *path, void *data)
 {
 	struct stat st;
-	struct object *obj = lookup_object(the_repository, oid->hash);
+	struct object *obj = lookup_object(the_repository, oid);
 
 	if (obj && obj->flags & SEEN)
 		return 0;
@@ -134,7 +134,7 @@ static int add_recent_packed(const struct object_id *oid,
 			     struct packed_git *p, uint32_t pos,
 			     void *data)
 {
-	struct object *obj = lookup_object(the_repository, oid->hash);
+	struct object *obj = lookup_object(the_repository, oid);
 
 	if (obj && obj->flags & SEEN)
 		return 0;
diff --git a/refs.c b/refs.c
index b8a8430c96..cd297ee4bd 100644
--- a/refs.c
+++ b/refs.c
@@ -379,7 +379,7 @@ static int filter_refs(const char *refname, const struct object_id *oid,
 
 enum peel_status peel_object(const struct object_id *name, struct object_id *oid)
 {
-	struct object *o = lookup_unknown_object(name->hash);
+	struct object *o = lookup_unknown_object(name);
 
 	if (o->type == OBJ_NONE) {
 		int type = oid_object_info(the_repository, name, NULL);
diff --git a/t/helper/test-example-decorate.c b/t/helper/test-example-decorate.c
index a20a6161e4..c8a1cde7d2 100644
--- a/t/helper/test-example-decorate.c
+++ b/t/helper/test-example-decorate.c
@@ -26,8 +26,8 @@ int cmd__example_decorate(int argc, const char **argv)
 	 * Add 2 objects, one with a non-NULL decoration and one with a NULL
 	 * decoration.
 	 */
-	one = lookup_unknown_object(one_oid.hash);
-	two = lookup_unknown_object(two_oid.hash);
+	one = lookup_unknown_object(&one_oid);
+	two = lookup_unknown_object(&two_oid);
 	ret = add_decoration(&n, one, &decoration_a);
 	if (ret)
 		BUG("when adding a brand-new object, NULL should be returned");
@@ -56,7 +56,7 @@ int cmd__example_decorate(int argc, const char **argv)
 	ret = lookup_decoration(&n, two);
 	if (ret != &decoration_b)
 		BUG("lookup should return added declaration");
-	three = lookup_unknown_object(three_oid.hash);
+	three = lookup_unknown_object(&three_oid);
 	ret = lookup_decoration(&n, three);
 	if (ret)
 		BUG("lookup for unknown object should return NULL");
diff --git a/tag.c b/tag.c
index 7445b8f6ea..5db870edb9 100644
--- a/tag.c
+++ b/tag.c
@@ -100,10 +100,9 @@ struct object *deref_tag_noverify(struct object *o)
 
 struct tag *lookup_tag(struct repository *r, const struct object_id *oid)
 {
-	struct object *obj = lookup_object(r, oid->hash);
+	struct object *obj = lookup_object(r, oid);
 	if (!obj)
-		return create_object(r, oid->hash,
-				     alloc_tag_node(r));
+		return create_object(r, oid, alloc_tag_node(r));
 	return object_as_type(r, obj, OBJ_TAG, 0);
 }
 
diff --git a/tree.c b/tree.c
index f416afc57d..4720945e6a 100644
--- a/tree.c
+++ b/tree.c
@@ -197,10 +197,9 @@ int read_tree(struct repository *r, struct tree *tree, int stage,
 
 struct tree *lookup_tree(struct repository *r, const struct object_id *oid)
 {
-	struct object *obj = lookup_object(r, oid->hash);
+	struct object *obj = lookup_object(r, oid);
 	if (!obj)
-		return create_object(r, oid->hash,
-				     alloc_tree_node(r));
+		return create_object(r, oid, alloc_tree_node(r));
 	return object_as_type(r, obj, OBJ_TREE, 0);
 }
 
diff --git a/upload-pack.c b/upload-pack.c
index b2a9f368ec..222cd3ad89 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -528,13 +528,13 @@ static int get_reachable_list(struct object_array *src,
 		return -1;
 
 	while ((i = read_in_full(cmd.out, namebuf, hexsz + 1)) == hexsz + 1) {
-		struct object_id sha1;
+		struct object_id oid;
 		const char *p;
 
-		if (parse_oid_hex(namebuf, &sha1, &p) || *p != '\n')
+		if (parse_oid_hex(namebuf, &oid, &p) || *p != '\n')
 			break;
 
-		o = lookup_object(the_repository, sha1.hash);
+		o = lookup_object(the_repository, &oid);
 		if (o && o->type == OBJ_COMMIT) {
 			o->flags &= ~TMP_MARK;
 		}
@@ -960,7 +960,7 @@ static void receive_needs(struct packet_reader *reader, struct object_array *wan
 static int mark_our_ref(const char *refname, const char *refname_full,
 			const struct object_id *oid)
 {
-	struct object *o = lookup_unknown_object(oid->hash);
+	struct object *o = lookup_unknown_object(oid);
 
 	if (ref_is_hidden(refname, refname_full)) {
 		o->flags |= HIDDEN_REF;
diff --git a/walker.c b/walker.c
index d74ae59c77..06cd2bd569 100644
--- a/walker.c
+++ b/walker.c
@@ -285,7 +285,7 @@ int walker_fetch(struct walker *walker, int targets, char **target,
 			error("Could not interpret response from server '%s' as something to pull", target[i]);
 			goto done;
 		}
-		if (process(walker, lookup_unknown_object(oids[i].hash)))
+		if (process(walker, lookup_unknown_object(&oids[i])))
 			goto done;
 	}