McDonald’s has launched “Free Fries Fridays,” a new promotion that will see the fast food chain giving away a free medium order of fries to customers every Friday through the end of the year.

“Free,” of course, is a word companies play a bit fast and loose with—and you will have to jump through a few hoops to get your hands on the salted, carb-filled goodness.

You will, for instance, have to download the McDonald’s app and opt into the rewards program after you’ve registered. You’ll also have to make an order of $1 or more to get the fries. And all orders must be from that mobile app and paid via contactless payment. You can’t just walk up to the counter and demand free food.

And, natch, you can only redeem the offer once per Friday.

This isn’t the first time McDonald’s has given out free food via its app. Last December, the chain offered everything from quirky McDonald’s merchandise to free or deeply discounted menu items to free food for life.

While it’s technically a burger joint, McDonald’s knows the drawing power of its fries. It has, in the past, made a fork out of French Fries and even topped them with chocolate. One location in Sydney, in 2016, only sold fries, bypassing the other menu options.

And it speaks to the popularity of the side item that after McDonald’s quit doing business in Russia following that country’s invasion of Ukraine, the biggest complaint from Russian citizens as the country opened up replacement restaurants was that they didn’t have the fries they wanted.