diff --git a/builtin/am.c b/builtin/am.c
index 1aea657a7f..ee7305eaa6 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1272,7 +1272,9 @@ static void get_commit_info(struct am_state *state, struct commit *commit)
 	buffer = logmsg_reencode(commit, NULL, get_commit_output_encoding());
 
 	ident_line = find_commit_header(buffer, "author", &ident_len);
-
+	if (!ident_line)
+		die(_("missing author line in commit %s"),
+		      oid_to_hex(&commit->object.oid));
 	if (split_ident_line(&id, ident_line, ident_len) < 0)
 		die(_("invalid ident line: %.*s"), (int)ident_len, ident_line);
 
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index c8f51bc65c..5876583220 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -610,12 +610,12 @@ 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, NULL);
+	struct object_entry *entry = packlist_find(&to_pack, oid);
 
 	if (entry)
 		entry->tagged = 1;
 	if (!peel_ref(path, &peeled)) {
-		entry = packlist_find(&to_pack, &peeled, NULL);
+		entry = packlist_find(&to_pack, &peeled);
 		if (entry)
 			entry->tagged = 1;
 	}
@@ -996,12 +996,11 @@ static int no_try_delta(const char *path)
  * few lines later when we want to add the new entry.
  */
 static int have_duplicate_entry(const struct object_id *oid,
-				int exclude,
-				uint32_t *index_pos)
+				int exclude)
 {
 	struct object_entry *entry;
 
-	entry = packlist_find(&to_pack, oid, index_pos);
+	entry = packlist_find(&to_pack, oid);
 	if (!entry)
 		return 0;
 
@@ -1141,13 +1140,12 @@ static void create_object_entry(const struct object_id *oid,
 				uint32_t hash,
 				int exclude,
 				int no_try_delta,
-				uint32_t index_pos,
 				struct packed_git *found_pack,
 				off_t found_offset)
 {
 	struct object_entry *entry;
 
-	entry = packlist_alloc(&to_pack, oid->hash, index_pos);
+	entry = packlist_alloc(&to_pack, oid);
 	entry->hash = hash;
 	oe_set_type(entry, type);
 	if (exclude)
@@ -1171,11 +1169,10 @@ static int add_object_entry(const struct object_id *oid, enum object_type type,
 {
 	struct packed_git *found_pack = NULL;
 	off_t found_offset = 0;
-	uint32_t index_pos;
 
 	display_progress(progress_state, ++nr_seen);
 
-	if (have_duplicate_entry(oid, exclude, &index_pos))
+	if (have_duplicate_entry(oid, exclude))
 		return 0;
 
 	if (!want_object_in_pack(oid, exclude, &found_pack, &found_offset)) {
@@ -1190,7 +1187,7 @@ static int add_object_entry(const struct object_id *oid, enum object_type type,
 
 	create_object_entry(oid, type, pack_name_hash(name),
 			    exclude, name && no_try_delta(name),
-			    index_pos, found_pack, found_offset);
+			    found_pack, found_offset);
 	return 1;
 }
 
@@ -1199,17 +1196,15 @@ static int add_object_entry_from_bitmap(const struct object_id *oid,
 					int flags, uint32_t name_hash,
 					struct packed_git *pack, off_t offset)
 {
-	uint32_t index_pos;
-
 	display_progress(progress_state, ++nr_seen);
 
-	if (have_duplicate_entry(oid, 0, &index_pos))
+	if (have_duplicate_entry(oid, 0))
 		return 0;
 
 	if (!want_object_in_pack(oid, 0, &pack, &offset))
 		return 0;
 
-	create_object_entry(oid, type, name_hash, 0, 0, index_pos, pack, offset);
+	create_object_entry(oid, type, name_hash, 0, 0, pack, offset);
 	return 1;
 }
 
@@ -1507,7 +1502,7 @@ static int can_reuse_delta(const unsigned char *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_oid, NULL);
+	base = packlist_find(&to_pack, &base_oid);
 	if (base) {
 		if (!in_same_island(&delta->idx.oid, &base->idx.oid))
 			return 0;
@@ -2568,7 +2563,7 @@ 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, NULL))
+	if (packlist_find(&to_pack, oid))
 		return;
 
 	tag = lookup_tag(the_repository, oid);
@@ -2592,7 +2587,7 @@ 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, NULL))      /* object packed? */
+	    packlist_find(&to_pack, &peeled))      /* object packed? */
 		add_tag_chain(oid);
 	return 0;
 }
@@ -2788,7 +2783,7 @@ 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, NULL);
+		ent = packlist_find(&to_pack, &obj->oid);
 		if (ent && depth > oe_tree_depth(&to_pack, ent))
 			oe_set_tree_depth(&to_pack, ent, depth);
 	}
@@ -3019,7 +3014,7 @@ 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, NULL) &&
+			if (!packlist_find(&to_pack, &oid) &&
 			    !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/bulk-checkin.c b/bulk-checkin.c
index 39ee7d6107..583aacb9e3 100644
--- a/bulk-checkin.c
+++ b/bulk-checkin.c
@@ -197,7 +197,7 @@ static int deflate_to_pack(struct bulk_checkin_state *state,
 	git_hash_ctx ctx;
 	unsigned char obuf[16384];
 	unsigned header_len;
-	struct hashfile_checkpoint checkpoint;
+	struct hashfile_checkpoint checkpoint = {0};
 	struct pack_idx_entry *idx = NULL;
 
 	seekback = lseek(fd, 0, SEEK_CUR);
diff --git a/diff-delta.c b/diff-delta.c
index e49643353b..77fea08dfb 100644
--- a/diff-delta.c
+++ b/diff-delta.c
@@ -326,6 +326,8 @@ create_delta(const struct delta_index *index,
 	const unsigned char *ref_data, *ref_top, *data, *top;
 	unsigned char *out;
 
+	*delta_size = 0;
+
 	if (!trg_buf || !trg_size)
 		return NULL;
 
diff --git a/pack-bitmap-write.c b/pack-bitmap-write.c
index fa78a460c9..a7a4964b50 100644
--- a/pack-bitmap-write.c
+++ b/pack-bitmap-write.c
@@ -144,7 +144,7 @@ static inline void reset_all_seen(void)
 
 static uint32_t find_object_pos(const struct object_id *oid)
 {
-	struct object_entry *entry = packlist_find(writer.to_pack, oid, NULL);
+	struct object_entry *entry = packlist_find(writer.to_pack, oid);
 
 	if (!entry) {
 		die("Failed to write bitmap index. Packfile doesn't have full closure "
diff --git a/pack-bitmap.c b/pack-bitmap.c
index 30842e1e74..e07c798879 100644
--- a/pack-bitmap.c
+++ b/pack-bitmap.c
@@ -1061,7 +1061,7 @@ int rebuild_existing_bitmaps(struct bitmap_index *bitmap_git,
 
 		entry = &bitmap_git->pack->revindex[i];
 		nth_packed_object_oid(&oid, bitmap_git->pack, entry->nr);
-		oe = packlist_find(mapping, &oid, NULL);
+		oe = packlist_find(mapping, &oid);
 
 		if (oe)
 			reposition[i] = oe_in_pack_pos(mapping, oe) + 1;
diff --git a/pack-objects.c b/pack-objects.c
index 52560293b6..c6250d77f4 100644
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -68,8 +68,7 @@ static void rehash_objects(struct packing_data *pdata)
 }
 
 struct object_entry *packlist_find(struct packing_data *pdata,
-				   const struct object_id *oid,
-				   uint32_t *index_pos)
+				   const struct object_id *oid)
 {
 	uint32_t i;
 	int found;
@@ -79,9 +78,6 @@ struct object_entry *packlist_find(struct packing_data *pdata,
 
 	i = locate_object_entry_hash(pdata, oid, &found);
 
-	if (index_pos)
-		*index_pos = i;
-
 	if (!found)
 		return NULL;
 
@@ -153,8 +149,7 @@ void prepare_packing_data(struct repository *r, struct packing_data *pdata)
 }
 
 struct object_entry *packlist_alloc(struct packing_data *pdata,
-				    const unsigned char *sha1,
-				    uint32_t index_pos)
+				    const struct object_id *oid)
 {
 	struct object_entry *new_entry;
 
@@ -177,12 +172,19 @@ struct object_entry *packlist_alloc(struct packing_data *pdata,
 	new_entry = pdata->objects + pdata->nr_objects++;
 
 	memset(new_entry, 0, sizeof(*new_entry));
-	hashcpy(new_entry->idx.oid.hash, sha1);
+	oidcpy(&new_entry->idx.oid, oid);
 
 	if (pdata->index_size * 3 <= pdata->nr_objects * 4)
 		rehash_objects(pdata);
-	else
-		pdata->index[index_pos] = pdata->nr_objects;
+	else {
+		int found;
+		uint32_t pos = locate_object_entry_hash(pdata,
+							&new_entry->idx.oid,
+							&found);
+		if (found)
+			BUG("duplicate object inserted into hash");
+		pdata->index[pos] = pdata->nr_objects;
+	}
 
 	if (pdata->in_pack)
 		pdata->in_pack[pdata->nr_objects - 1] = NULL;
diff --git a/pack-objects.h b/pack-objects.h
index 857d43850b..6fe6ae5ee8 100644
--- a/pack-objects.h
+++ b/pack-objects.h
@@ -183,12 +183,10 @@ static inline void packing_data_unlock(struct packing_data *pdata)
 }
 
 struct object_entry *packlist_alloc(struct packing_data *pdata,
-				    const unsigned char *sha1,
-				    uint32_t index_pos);
+				    const struct object_id *oid);
 
 struct object_entry *packlist_find(struct packing_data *pdata,
-				   const struct object_id *oid,
-				   uint32_t *index_pos);
+				   const struct object_id *oid);
 
 static inline uint32_t pack_name_hash(const char *name)
 {
diff --git a/t/helper/test-read-cache.c b/t/helper/test-read-cache.c
index 7e79b555de..244977a29b 100644
--- a/t/helper/test-read-cache.c
+++ b/t/helper/test-read-cache.c
@@ -4,11 +4,10 @@
 
 int cmd__read_cache(int argc, const char **argv)
 {
-	int i, cnt = 1, namelen;
+	int i, cnt = 1;
 	const char *name = NULL;
 
 	if (argc > 1 && skip_prefix(argv[1], "--print-and-refresh=", &name)) {
-		namelen = strlen(name);
 		argc--;
 		argv++;
 	}
@@ -24,7 +23,7 @@ int cmd__read_cache(int argc, const char **argv)
 
 			refresh_index(&the_index, REFRESH_QUIET,
 				      NULL, NULL, NULL);
-			pos = index_name_pos(&the_index, name, namelen);
+			pos = index_name_pos(&the_index, name, strlen(name));
 			if (pos < 0)
 				die("%s not in index", name);
 			printf("%s is%s up to date\n", name,