Sleep recommendations

Okay, so my baby is almost 4 months old and still like to sleep in a halo sleep sack swaddle. The problem is that yesterday he mastered rolling from his back to his belly and now I do t feel comfortable trapping his arms while he sleeps like that. We tried sleeping without the swaddle last night and that was a disaster. He was flailing his arms, startling himself or hitting himself in the face all night long.