In celebration of the total solar eclipse, Burger King is offering a BOGO deal on its Whopper sandwiches.

On April 8, 15 states will be in the path of totality, while the rest of the continental United States will get a partial eclipse. According to NASA, the next total solar eclipse will be Aug. 23, 2044.

To celebrate the rare occasion, the fast-food conglomerate will give away Whopper sandwiches all day to its Royal Perks members with a buy-one-get-one deal.

Here’s how to score a free Whopper:

  • Text ECLIPSE to 251251
  • If you’re not a Royal Perk member, sign up either online or through the Burger King app
  • Use the code at checkout.

The deal is available April 8-15.