Night Feedings

My son will be five months on the 25th. He's sleeping so much better than he was before and can fall asleep on his own. He wakes up every 3.5-4.5 hours at night to eat. (He's formula fed) I've tried leaving him for a few minutes when he starts to stir but he goes into a full blown cry, so I go in and feed him. I've tried to just pat him and see if he'll go back but he continues to cry until I feed him. I have read that babies his age should be sleeping longer at night. Does this seem normal? I would love to wean him of one of his night feedings but I don't want him to go hungry either!! I'm a first time mom so I'm not completely sure of what's normal for his age.