[kirenida]

Related question: what method do you use to keep the duvet in place inside the cover?

I have some animal themed safety pins that my parents used on my duvet since I was a child. I put four of them in a square shape around the middle of the cover when the duvet is inside.

[dgfitz]

It just stays.

[sunshowers]

My duvet covers have ties you can use against any duvet.

My parents used to use safety pins.

[mlok]

If needed, I grab a cover border, and align the duvet border within it, make sure corners are aligned too, and then again : shake it. It comes back to place.

[Chaosvex]

Buttons? A zip? I've never seen a cover that doesn't have a way of keeping it closed.

[kirenida]

Keeping it closed is not the problem.

The problem is that the duvet bunches up inside the cover if you move around a lot during sleep.