Storing multiple messages in one protocol buffer binary file

I have repeating messages which I want to store in a single file. Currently I have to wrap this repeating message in another message. Is there a way around this?

package foo;

message Box {
  required int32 tl_x = 1;
  required int32 tl_y = 2;
  required int32 w = 3;
  required int32 h = 4;
}

message Boxes {
  repeated Box boxes = 1;
}