Last week, Netflix announced that it was ending support for older devices from Samsung, Roku, and Vizio after December 1st, but it wasn’t clear exactly why those devices were losing support, besides the fact that they were old. And a Netflix support doc isn’t helpful, saying that the problem is due to “technical limitations.” But Netflix has shared a little more detail about those technical limitations on older Roku devices with Gizmodo, and it turns out the answer is quite simple: DRM.

Here’s what’s going on: Netflix has used Microsoft’s PlayReady DRM since 2010 so that it could more easily bring its streaming service to the loads of TVs, devices, and set top boxes you can find it on today while satisfying its content providers that their work wouldn’t get pirated. But because Netflix had already shipped devices like the affected Rokus with an earlier form of the deprecated Windows Media DRM, they would inevitably get left behind if Netflix ever cut ties with the old DRM standard and if those devices couldn’t be upgraded to the newer PlayReady instead.

Now, it has — and they can’t, and Netflix tells The Verge that older Samsung and Vizio devices are losing support for Netflix for the same reason.

Update, November 13th, 5:00PM ET: Added confirmation from Netflix that Windows Media DRM is the reason the older Samsung and Vizio devices are also losing support for Netflix.