5 month old rolling on stomach at Night

My five month old insists on sleeping on his stomach at night. As soon as we put him in bed, he rolls right onto his stomach. It’s impossible to get him to stay on his back so all night, every 30 minutes or so we are getting up and moving him which he hates so then it takes us an hour to get him back to sleep. He can’t roll onto his back so I’m nervous to leave him on his stomach. I feel weird calling his pediatrician about a small-no-big-deal matter but I don’t want to keep having to get up all night long to flip him back. We keep reading it’s fine as long as they long as he can roll back but since he can’t we aren’t sure what to do. What are your guys thoughts and suggestions?