Shake Shack is announcing it’s offering free Chicken Shack sandwiches every Sunday in April starting this Sunday, April 7—one-upping a famously “closed on Sundays” chicken sandwich fast-food chain, which shall remain unnamed. Shake Shack’s Chicken Shack is made with crispy, white-meat chicken breast – always fresh, never frozen, and antibiotic-free (a pledge Shake Shack plans to keep, unlike other chains) – over lettuce, pickles and buttermilk herb mayo on a toasted potato bun.

Here’s how the promo works:

Place a minimum $10 Shake Shack order via kiosk in-Shack or via the Shake Shack app or website for delivery or pick-up.

Enter promo code CHICKENSUNDAY for one free Chicken Shack. Limit one free sandwich per order.

Once items are added to the cart, the offer will automatically apply.

The promo is available Sunday, April 7; Sunday, April 14; Sunday, April 21 and Sunday, April 28 at all U.S. Shacks, excluding those at airports, stadiums, arenas, travel plazas and museums.