diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index e8c71fc1d2..cafaab7b13 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -549,13 +549,13 @@ static void *unpack_data(struct object_entry *obj,
 			 void *cb_data)
 {
 	off_t from = obj[0].idx.offset + obj[0].hdr_size;
-	unsigned long len = obj[1].idx.offset - from;
+	off_t len = obj[1].idx.offset - from;
 	unsigned char *data, *inbuf;
 	git_zstream stream;
 	int status;
 
 	data = xmallocz(consume ? 64*1024 : obj->size);
-	inbuf = xmalloc((len < 64*1024) ? len : 64*1024);
+	inbuf = xmalloc((len < 64*1024) ? (int)len : 64*1024);
 
 	memset(&stream, 0, sizeof(stream));
 	git_inflate_init(&stream);
@@ -563,15 +563,15 @@ static void *unpack_data(struct object_entry *obj,
 	stream.avail_out = consume ? 64*1024 : obj->size;
 
 	do {
-		ssize_t n = (len < 64*1024) ? len : 64*1024;
+		ssize_t n = (len < 64*1024) ? (ssize_t)len : 64*1024;
 		n = xpread(get_thread_data()->pack_fd, inbuf, n, from);
 		if (n < 0)
 			die_errno(_("cannot pread pack file"));
 		if (!n)
-			die(Q_("premature end of pack file, %lu byte missing",
-			       "premature end of pack file, %lu bytes missing",
-			       len),
-			    len);
+			die(Q_("premature end of pack file, %"PRIuMAX" byte missing",
+			       "premature end of pack file, %"PRIuMAX" bytes missing",
+			       (unsigned int)len),
+			    (uintmax_t)len);
 		from += n;
 		len -= n;
 		stream.next_in = inbuf;