You might have to be extra careful who you buy your used Nintendo Switch game cards from if you don’t want to get mistakenly banned. A Nintendo Switch 2 owner posted on Reddit that they got banned after downloading patches for a few Switch game cards that were bought off Facebook Marketplace.

Reddit user dmanthey said they inserted each game into their Switch 2 to patch, but found out that their online services were restricted the day after. The Switch 2 user contacted Nintendo support and discovered they were banned, but provided proof of purchase and was unbanned shortly after. The Redditor said the “whole process was painless and fluid,” but this reactionary banning protocol may be an alarming precedent for anyone looking to save a few dollars by buying used games.

To understand why this happened, it’s important to note that Nintendo attaches unique codes to its Switch game cartridges to prevent piracy. However, bad actors can copy games onto a third-party device, like the MIG Flash, and then resell the physical game card. Once Nintendo detects two instances of its unique code being online at the same time, it will ban any accounts using it. Anyone pirating Nintendo’s software understands this is a potential consequence, but it would come as an annoying surprise to oblivious second-hand buyers. After proving they bought the Switch games, Redditor dmanthey said they were told the cartridges were fine and even able to be resold.

This anti-piracy policy isn’t new — Nintendo has long had a reputation for fiercely combating any type of piracy – but it has become relevant again thanks to the recently released Switch 2, which offers backwards compatibility with original Switch titles. The company even recently amended its user agreement to allow itself the power to brick a Nintendo Switch that’s caught running pirated games or mods.