diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index de35960d99bb6c92c0f57c588aa6f43e3c227d2c..54b089542b91fe786f4f75fe363cd1d5fb1635ff 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -207,8 +207,13 @@ static unsigned check_object(struct object *obj)
 	if (!(obj->flags & FLAG_CHECKED)) {
 		unsigned long size;
 		int type = sha1_object_info(obj->sha1, &size);
-		if (type != obj->type || type <= 0)
-			die(_("object of unexpected type"));
+		if (type <= 0)
+			die(_("did not receive expected object %s"),
+			      sha1_to_hex(obj->sha1));
+		if (type != obj->type)
+			die(_("object %s: expected type %s, found %s"),
+			    sha1_to_hex(obj->sha1),
+			    typename(obj->type), typename(type));
 		obj->flags |= FLAG_CHECKED;
 		return 1;
 	}