To take advantage of the offer, simply order a Classic Burger in the app on National Hamburger Day and you’ll qualify for a second one for free.

While prices vary, a Classic Burger goes for $7.49 at my nearest Wayback Burgers location.

Wayback’s Classic Burger features two beef patties cooked-to-order, American cheese, lettuce, tomato, pickles, onions, and ketchup and mustard on a toasted split top bun.

National Hamburger Day is celebrated annually on May 28.

Image via Wayback Burgers