Can’t read the kanji characters on the label? You’re not the only one, so here’s a shopping secret to help you out.

Going to buy milk at the store in Japan can be a little tricky for foreigners. See, while all those paper cartons with pictures of white, creamy liquids on them night look like moo juice, that’s not necessarily the case.

Generally right next to the milk on the shelves of Japanese grocery and convenience stores you can find a selection of other dairy-based concoctions. These could be milk mixed with butter, dry milk, water, coffee, or fruit flavorings, potentially giving you something richer, thinner, or quite different-tasting than the milk you actually want to buy.

If you can read kanji, Japan’s non-phonetic writing system, you can differentiate between gyuunyuu/牛乳 milk, and nyuuseihin/乳製品, as the not-quite-milk products are called, by reading the text printed on the carton. But even if Japanese is all Greek to you, there’s a way to tell them apart, as explained by Japanese Twitter user @inodogs.

See, sometimes even native Japanese shoppers sometimes grab the wrong carton by mistake, and @inodogs was telling his younger brother, a professional chef, about a time when he ended up with nyuuseihin when he wanted gyuunyuu. So his brother clued him in on a little-known secret: if the carton has a little piece cut out of its top ridge, as shown in the red circle in @imodog’s tweet, that means it’s ordinary milk/gyuunyuu.

This revelation sent shockwaves through Japanese Twitter, with tens of thousands of excited, newly-informed individuals helping to spread the world with likes and retweets. But while this knowledge is a boon to foreigners struggling with kanji or people of any nationality who simply aren’t paying attention, the cutout isn’t originally for their benefit. Instead, it’s there to help blind or vision-impaired shoppers find milk, as part of an initiative that was started in early 2000.

It’s worth noting that not every milk producer in Japan conforms to this standard. But if you’re at the store and do see a carton with a piece missing from the top, you can be sure it’s milk, even if you’ve got no idea what the packaging says.

Source: IT Media, Twitter/@inodogs