Rolling over in the crib

My 4 month old has figured out how to roll from her back to her belly on her play mat. Well last night she did it in her crib while we all slept. The problem is she can't roll from her belly to her back yet. She woke me up fussing because she was stuck. I immediately panicked when I saw her. I have no idea what to do now because I feel like that's too unsafe! Any suggestions? I'm never gonna sleep again!