Microsoft made a lot of Xbox One owners happy this week when it announced new DVR functionality coming to the game console, complete with the ability to record and play back live over-the-air television.

The service is free, but we’re learning now there will be a couple caveats.

A Microsoft spokesperson confirms you’ll only be able to record TV if you have an external hard drive. You won’t be able to use the console’s internal memory because the company wants to keep the “[storage] paths optimized” by keeping the different filetypes separate, according to GameSpot.

Microsoft recently partnered with Seagate to announce a 2 TB external hard drive designed specifically for Xbox One and Xbox 360. The device would offer plenty of storage space when it launches later this year, but it does cost $110.

GameSpot also reports that a feature that allows users to transfer recordings from their Xbox to a mobile device will only work with Windows 10 machines. Android and iPhone users, for instance, can still pause live television on an Xbox One console, but they won’t be able to transfer files to watch on their smartphone later.

And, of course, the final requirement is a TV tuner, which doesn’t come built in with Xbox consoles right now. A Hauppauge WinTV-955Q does the trick, but it costs $80.

Microsoft will roll out the new DVR features in 2016, and it certainly will be a big step forward for many cord-cutters. But — like most things in tech — there will be some drawbacks.