Pack and play mattress

Anyone else feel guilty for how hard these pack and play mattresses are? They shouldn't be called mattresses they should be called boards because that is what they feel like. Ours is so hard and firm with maybe a quarter inch of foam on it and that's it. Has anyone done anything different to help soften the mattress but still keep it safe for the baby? I know you aren't suppose to add things to it that didn't come with the set for safety reasons but dang, who would want to sleep through the night on a hard as rock board??