The sandwich chain will reportedly be handing out free breakfast for a full 31 days. The entire month of May, you can walk into a Subway sandwich shop and walk out with one of Subway’s six-inch breakfast sandwiches for free—Bacon, Egg & Cheese, Black Forest Ham, Egg & Cheese, Steak, Egg Whites & Cheese, or just a regular Egg & Cheese.

However, there’s a huge catch. According to Business Insider, you can only take advantage of the offer before 9 a.m and you actually have to buy a sub sandwich along with your breakfast. So you have to make sure you get there on time, commit to eating Subway twice in one day, and spend money. So is it really “free?”

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Breakfast has been a significant sales booster for other fast food chains. McDonald’s, which recently reported its quarterly earnings, saw a fairly large increase in sales since introducing all-day breakfast. Taco Bell introduced breakfast items just two years ago, and they now make up about 6% of the restaurant’s business.

Aside from trying to get in on the breakfast game, Subway is also committing to fresher ingredients. It introduced a chicken sandwich with antibiotic-free meat for the first time in its history last month, and is transitioning towards serving exclusively antibiotic-free chicken.