nice shirt but shrink after first wash

the shirt is really. nice, my son loves it when he tried on, but it shrank significantly after the first wash (in cold water in handwash cycle), To the extend that the shirt is smaller than a new size S in the same style (I ordered two sizes as my son is in-betwees S and M). I had to return both sizes trying to order a size L this time, hoping after wash, it will shrink down to a size M.