diff --git a/blame.c b/blame.c
index 888dec1a38..34380a6fb8 100644
--- a/blame.c
+++ b/blame.c
@@ -2861,20 +2861,18 @@ void setup_scoreboard(struct blame_scoreboard *sb,
 		sb->final_buf_size = o->file.size;
 	}
 	else {
-		size_t final_buf_size_st = 0;
 		o = get_origin(sb->final, sb->path);
 		if (fill_blob_sha1_and_mode(sb->repo, o))
 			die(_("no such path %s in %s"), sb->path, final_commit_name);
 
 		if (sb->revs->diffopt.flags.allow_textconv &&
 		    textconv_object(sb->repo, sb->path, o->mode, &o->blob_oid, 1, (char **) &sb->final_buf,
-				    &final_buf_size_st))
+				    &sb->final_buf_size))
 			;
 		else
 			sb->final_buf = odb_read_object(the_repository->objects,
 							&o->blob_oid, &type,
-							&final_buf_size_st);
-		sb->final_buf_size = cast_size_t_to_ulong(final_buf_size_st);
+							&sb->final_buf_size);
 
 		if (!sb->final_buf)
 			die(_("cannot read blob %s for path %s"),
diff --git a/blame.h b/blame.h
index 3b34be0e5c..1b66084a8d 100644
--- a/blame.h
+++ b/blame.h
@@ -117,7 +117,7 @@ struct blame_scoreboard {
 	 * indexed with scoreboard.lineno[blame_entry.lno].
 	 */
 	char *final_buf;
-	unsigned long final_buf_size;
+	size_t final_buf_size;
 
 	/* linked list of blames */
 	struct blame_entry *ent;
diff --git a/builtin/fast-import.c b/builtin/fast-import.c
index cef98d8fde..b0e79f8c0f 100644
--- a/builtin/fast-import.c
+++ b/builtin/fast-import.c
@@ -962,7 +962,7 @@ static int store_object(
 	struct object_entry *e;
 	unsigned char hdr[96];
 	struct object_id oid;
-	unsigned long hdrlen, deltalen;
+	size_t hdrlen, deltalen;
 	struct git_hash_ctx c;
 	git_zstream s;
 	struct repo_config_values *cfg = repo_config_values(the_repository);
@@ -998,13 +998,10 @@ static int store_object(
 
 	if (last && last->data.len && last->data.buf && last->depth < max_depth
 		&& dat->len > the_hash_algo->rawsz) {
-		size_t deltalen_st = 0;
-
 		delta_count_attempts_by_type[type]++;
 		delta = diff_delta(last->data.buf, last->data.len,
 			dat->buf, dat->len,
-			&deltalen_st, dat->len - the_hash_algo->rawsz);
-		deltalen = cast_size_t_to_ulong(deltalen_st);
+			&deltalen, dat->len - the_hash_algo->rawsz);
 	} else
 		delta = NULL;
 
@@ -1240,10 +1237,9 @@ out:
  */
 static void *gfi_unpack_entry(
 	struct object_entry *oe,
-	unsigned long *sizep)
+	size_t *sizep)
 {
 	enum object_type type;
-	size_t size_st = 0;
 	void *data;
 	struct packed_git *p = all_packs[oe->pack_id];
 	if (p == pack_data && p->pack_size < (pack_size + the_hash_algo->rawsz)) {
@@ -1266,9 +1262,7 @@ static void *gfi_unpack_entry(
 		 */
 		p->pack_size = pack_size + the_hash_algo->rawsz;
 	}
-	data = unpack_entry(the_repository, p, oe->idx.offset, &type, &size_st);
-	if (sizep)
-		*sizep = cast_size_t_to_ulong(size_st);
+	data = unpack_entry(the_repository, p, oe->idx.offset, &type, sizep);
 	return data;
 }
 
@@ -1277,7 +1271,7 @@ static void load_tree(struct tree_entry *root)
 	struct object_id *oid = &root->versions[1].oid;
 	struct object_entry *myoe;
 	struct tree_content *t;
-	unsigned long size;
+	size_t size;
 	char *buf;
 	const char *c;
 
@@ -1295,10 +1289,8 @@ static void load_tree(struct tree_entry *root)
 			die(_("can't load tree %s"), oid_to_hex(oid));
 	} else {
 		enum object_type type;
-		size_t size_st = 0;
 		buf = odb_read_object(the_repository->objects, oid, &type,
-				      &size_st);
-		size = cast_size_t_to_ulong(size_st);
+				      &size);
 		if (!buf || type != OBJ_TREE)
 			die(_("can't load tree %s"), oid_to_hex(oid));
 	}
@@ -2616,7 +2608,7 @@ static void file_change_deleteall(struct branch *b)
 	b->num_notes = 0;
 }
 
-static void parse_from_commit(struct branch *b, char *buf, unsigned long size)
+static void parse_from_commit(struct branch *b, char *buf, size_t size)
 {
 	if (!buf || size < the_hash_algo->hexsz + 6)
 		die(_("not a valid commit: %s"), oid_to_hex(&b->oid));
@@ -2633,13 +2625,11 @@ static void parse_from_existing(struct branch *b)
 		oidclr(&b->branch_tree.versions[0].oid, the_repository->hash_algo);
 		oidclr(&b->branch_tree.versions[1].oid, the_repository->hash_algo);
 	} else {
-		unsigned long size;
-		size_t size_st = 0;
+		size_t size;
 		char *buf;
 
 		buf = odb_read_object_peeled(the_repository->objects, &b->oid,
-					     OBJ_COMMIT, &size_st, &b->oid);
-		size = cast_size_t_to_ulong(size_st);
+					     OBJ_COMMIT, &size, &b->oid);
 		parse_from_commit(b, buf, size);
 		free(buf);
 	}
@@ -2668,7 +2658,7 @@ static int parse_objectish(struct branch *b, const char *objectish)
 		if (!oideq(&b->oid, &oe->idx.oid)) {
 			oidcpy(&b->oid, &oe->idx.oid);
 			if (oe->pack_id != MAX_PACK_ID) {
-				unsigned long size;
+				size_t size;
 				char *buf = gfi_unpack_entry(oe, &size);
 				parse_from_commit(b, buf, size);
 				free(buf);
@@ -3334,15 +3324,13 @@ static void cat_blob_write(const char *buf, unsigned long size)
 static void cat_blob(struct object_entry *oe, struct object_id *oid)
 {
 	struct strbuf line = STRBUF_INIT;
-	unsigned long size;
+	size_t size;
 	enum object_type type = 0;
 	char *buf;
 
 	if (!oe || oe->pack_id == MAX_PACK_ID) {
-		size_t size_st = 0;
 		buf = odb_read_object(the_repository->objects, oid, &type,
-				      &size_st);
-		size = cast_size_t_to_ulong(size_st);
+				      &size);
 	} else {
 		type = oe->type;
 		buf = gfi_unpack_entry(oe, &size);
@@ -3421,7 +3409,7 @@ static void parse_cat_blob(const char *p)
 static struct object_entry *dereference(struct object_entry *oe,
 					struct object_id *oid)
 {
-	unsigned long size;
+	size_t size;
 	char *buf = NULL;
 	const unsigned hexsz = the_hash_algo->hexsz;
 
@@ -3450,10 +3438,8 @@ static struct object_entry *dereference(struct object_entry *oe,
 		buf = gfi_unpack_entry(oe, &size);
 	} else {
 		enum object_type unused;
-		size_t size_st = 0;
 		buf = odb_read_object(the_repository->objects, oid,
-				      &unused, &size_st);
-		size = cast_size_t_to_ulong(size_st);
+				      &unused, &size);
 	}
 	if (!buf)
 		die(_("can't load object %s"), oid_to_hex(oid));
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 83b0431c21..0ae3bb10af 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -353,21 +353,17 @@ static void index_commit_for_bitmap(struct commit *commit)
 
 static void *get_delta(struct object_entry *entry)
 {
-	unsigned long size, base_size;
-	size_t delta_size;
+	size_t size, base_size, delta_size;
 	void *buf, *base_buf, *delta_buf;
 	enum object_type type;
-	size_t size_st = 0, base_size_st = 0;
 
 	buf = odb_read_object(the_repository->objects, &entry->idx.oid,
-			      &type, &size_st);
-	size = cast_size_t_to_ulong(size_st);
+			      &type, &size);
 	if (!buf)
 		die(_("unable to read %s"), oid_to_hex(&entry->idx.oid));
 	base_buf = odb_read_object(the_repository->objects,
 				   &DELTA(entry)->idx.oid, &type,
-				   &base_size_st);
-	base_size = cast_size_t_to_ulong(base_size_st);
+				   &base_size);
 	if (!base_buf)
 		die("unable to read %s",
 		    oid_to_hex(&DELTA(entry)->idx.oid));
@@ -385,11 +381,11 @@ static void *get_delta(struct object_entry *entry)
 	return delta_buf;
 }
 
-static unsigned long do_compress(void **pptr, unsigned long size)
+static size_t do_compress(void **pptr, size_t size)
 {
 	git_zstream stream;
 	void *in, *out;
-	unsigned long maxsize;
+	size_t maxsize;
 	struct repo_config_values *cfg = repo_config_values(the_repository);
 
 	git_deflate_init(&stream, cfg->pack_compression_level);
@@ -515,7 +511,7 @@ static inline int oe_size_greater_than(struct packing_data *pack,
 static unsigned long write_no_reuse_object(struct hashfile *f, struct object_entry *entry,
 					   unsigned long limit, int usable_delta)
 {
-	unsigned long size, datalen;
+	size_t size, datalen;
 	unsigned char header[MAX_PACK_OBJECT_HEADER],
 		      dheader[MAX_PACK_OBJECT_HEADER];
 	unsigned hdrlen;
@@ -534,11 +530,9 @@ static unsigned long write_no_reuse_object(struct hashfile *f, struct object_ent
 			type = st->type;
 			size = st->size;
 		} else {
-			size_t size_st = 0;
 			buf = odb_read_object(the_repository->objects,
 					      &entry->idx.oid, &type,
-					      &size_st);
-			size = cast_size_t_to_ulong(size_st);
+					      &size);
 			if (!buf)
 				die(_("unable to read %s"),
 				    oid_to_hex(&entry->idx.oid));
@@ -2788,8 +2782,7 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
 {
 	struct object_entry *trg_entry = trg->entry;
 	struct object_entry *src_entry = src->entry;
-	unsigned long trg_size, src_size, sizediff, max_size, sz;
-	size_t delta_size;
+	size_t trg_size, src_size, delta_size, sizediff, max_size, sz;
 	unsigned ref_depth;
 	enum object_type type;
 	void *delta_buf;
@@ -2842,12 +2835,10 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
 
 	/* Load data if not already done */
 	if (!trg->data) {
-		size_t sz_st = 0;
 		packing_data_lock(&to_pack);
 		trg->data = odb_read_object(the_repository->objects,
 					    &trg_entry->idx.oid, &type,
-					    &sz_st);
-		sz = cast_size_t_to_ulong(sz_st);
+					    &sz);
 		packing_data_unlock(&to_pack);
 		if (!trg->data)
 			die(_("object %s cannot be read"),
@@ -2859,12 +2850,10 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
 		*mem_usage += sz;
 	}
 	if (!src->data) {
-		size_t sz_st = 0;
 		packing_data_lock(&to_pack);
 		src->data = odb_read_object(the_repository->objects,
 					    &src_entry->idx.oid, &type,
-					    &sz_st);
-		sz = cast_size_t_to_ulong(sz_st);
+					    &sz);
 		packing_data_unlock(&to_pack);
 		if (!src->data) {
 			if (src_entry->preferred_base) {
diff --git a/git-compat-util.h b/git-compat-util.h
index 0fb51b936b..e0f50a277b 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -699,15 +699,6 @@ static inline size_t st_left_shift(size_t a, unsigned shift)
 	return a << shift;
 }
 
-static inline unsigned long cast_size_t_to_ulong(size_t a)
-{
-	if (a != (unsigned long)a)
-		die("object too large to read on this platform: %"
-		    PRIuMAX" is cut off to %lu",
-		    (uintmax_t)a, (unsigned long)a);
-	return (unsigned long)a;
-}
-
 static inline uint32_t cast_size_t_to_uint32_t(size_t a)
 {
 	if (a != (uint32_t)a)
diff --git a/t/helper/test-pack-deltas.c b/t/helper/test-pack-deltas.c
index 959705feca..8b448485fb 100644
--- a/t/helper/test-pack-deltas.c
+++ b/t/helper/test-pack-deltas.c
@@ -18,7 +18,7 @@ static const char *usage_str[] = {
 	NULL
 };
 
-static unsigned long do_compress(void **pptr, unsigned long size)
+static size_t do_compress(void **pptr, size_t size)
 {
 	git_zstream stream;
 	void *in, *out;
@@ -48,8 +48,8 @@ static void write_ref_delta(struct hashfile *f,
 			    struct object_id *base)
 {
 	unsigned char header[MAX_PACK_OBJECT_HEADER];
-	unsigned long delta_size, compressed_size, hdrlen;
-	size_t size, base_size, delta_size_st = 0;
+	unsigned long compressed_size, hdrlen;
+	size_t size, base_size, delta_size;
 	enum object_type type;
 	void *base_buf, *delta_buf;
 	void *buf = odb_read_object(the_repository->objects,
@@ -65,8 +65,7 @@ static void write_ref_delta(struct hashfile *f,
 		die("unable to read %s", oid_to_hex(base));
 
 	delta_buf = diff_delta(base_buf, base_size,
-			       buf, size, &delta_size_st, 0);
-	delta_size = cast_size_t_to_ulong(delta_size_st);
+			       buf, size, &delta_size, 0);
 
 	compressed_size = do_compress(&delta_buf, delta_size);