On Friday, Dec. 3, and Saturday, Dec. 4, Burger King restaurants nationwide will be serving Whoppers for their original price of just 37 cents. The deal comes with a catch, however — it’s only available to Burger King Royal Perks members who order via the Burger King app or website.

“In 1957, Burger King changed the game with the introduction of the Whopper sandwich – an iconic, flame-grilled burger prepared YOUR way (with 1,024 potential combinations, to be exact),” writes Zahra Nurani, Burger King North America’s head of marketing communications, in a statement. “And now, 64 years later, we’re excited to celebrate our beloved burger by offering The Whopper for its original price of 37 cents exclusively to Royal Perks members.”

Customers wishing to redeem the discounted Whoppers can sign up for a Royal Perks account by downloading the BK app or visiting BK.com/BKRewards. Once registered, customers are instructed to add the Whopper coupon before placing their order.

The offer is valid at participating restaurants in the U.S. (excluding Alaska and Hawaii) on Dec. 3 and Dec. 4 only. Royal Perks members are limited to one offer per account.