If you’re short on cash (or rather, bottle caps) in Fallout 4, here’s an easy way to make more.

Bethesda’s new open-world role-playing game, out now on PlayStation 4, Xbox One, and PC, is kind of riddled with bugs, and one of them provides players with an easy, virtually unlimited source of in-game currency, reports Eurogamer. It likely won’t last long as Bethesda will want to stop players from cheating the system, but it’s currently a good way of getting your hands on some decent gear, particularly early in the game.

The glitch works with most vendors. You’ll need to have a decent stock of bottle caps to start; then go and buy up all of one type of ammo from the vendor. You then need to sell back one of the rounds — but only one — without finalizing the deal. Next, sell all the remaining ammo, but again, don’t finalize the deal.

You’ll find that one of the rounds of ammo stays in your inventory, and you can keep selling this to the vendor until they’re all out of bottle caps. When you’re stripped one vendor of their caps, you’ll need to head elsewhere to try again or come back in 24 hours when their caps are replenished.