The Mario Tennis Aces demo is live, giving players the chance to try out the game before its launch on Nintendo Switch on June 22—and, more importantly, players are starting to learn new information about the game.

GameXplain recently discovered that the game is compatible with a GameCube controller if a player owns the relevant Wii U GameCube controller adaptor that was originally sold alongside Super Smash Bros. for Wii in November 2014.

This was made possible by a patch for the Switch last fall that saw Nintendo include support for the Wii U’s controller adaptor out of nowhere. GameCube controllers also work with other Nintendo Switch titles, like Mario Kart 8 Deluxe.

To use the adaptor (if you can find one), all you need to do is make sure your Nintendo Switch is patched correctly and attach the two USB connections into the console. An official Wii U controller adaptor is hard to find, however, with most being sold for ridiculous prices on eBay at the time of writing.

It’s interesting, however, that the Nintendo Switch allows GameCube controller users to play with the original button layout from the Nintendo GameCube version of Mario Tennis, Mario Power Tennis.

Mario Tennis Aces uses a single-button layout for its different shots, whereas Mario Power Tennis allowed players to do shots when buttons were pressed in a certain order. A lob shot, for example, can be used on a GameCube controller when the user presses A then B.

If you can’t play the demo, don’t worry—Mario Tennis Aces will be released for the Nintendo Switch on June 22.