Wayback Burgers is taking advantage of the extra day this leap year to give a sweet treat to guests with the Wayback app.

“A special day deserves a special deal,” says Patrick Conlin, President of Wayback Burgers. “Since an extra day added to February is a treat, we knew the best way to celebrate is to sweeten the deal on our many delicious flavors of milkshakes.”

Wayback Burgers will offer its indulgent hand-dipped milkshakes to guests with the Wayback app for only $2.29 on February 29. The offer is good for all flavors, including Vanilla, Chocolate, Strawberry, Black & White, Coffee, Cafe Mocha, Oreo Mud Pie, Oreo Mint, Chocolate Banana, Strawberry Banana, and Cookies ‘n Cream. Shakes at Wayback Burgers are crafted to order with Blue Bunny ice cream and whole milk.

The special deal is only available to users of the Wayback App, which is available for download on the Apple store or Google Play. Simply order your milkshake on the app to get the special price. No other purchase is required.

Milkshakes have always been special at Wayback Burgers, and a point of focus in celebrations and special programs. For instance, as a supporter of the Boys & Girls Clubs of America, Wayback Burgers not only raises money ($15,685.79 last year) but engaged the kids in a Shake-Naming Contest. The winning shake was made available for a limited time. The burger brand also celebrates the first day of summer with Free Shake Day, handing out 28,000 free Black & White shakes, last year.

“Celebrations typically mean dessert, and in the Wayback Burgers world, that means treating yourself to a hand-dipped milkshake,” Conlin adds. “We love opportunities to enjoy special occasions with our guests over delicious shakes.”