Toddler duvet

Weve transferred to a duvet in the past 3 weeks or so and he sleeps great with it however if he gets out of it for some reason, he's struggling to get back in it (room is pitch black). We've never really had to go in at night but now going in just to put the duvet back over him. Does this happen to anyone else and if so, did you do anything to help/change it? It's not necessarily me getting up because I put it over him and he falls back to sleep but I'd love to be able to help him in some way Unless he will just be able to do it the older he gets? Thank you in advance!