Starbucks has reached a deal with Delta Airlines to award every $1 spent at Starbucks with a 1 mile Delta SkyMiles credit.

The two companies announced the partnership Wednesday. Starbucks and Delta customers can link their accounts either at detlastarbucks.com or starbucksdelta.com.

On days when customers are flying Delta and make a Starbucks purchase, they will get double the rewards points.

To promote the new venture, anyone who signs up for the rewards program by Dec. 31 will get 500 additional SkyMiles and, after making one Starbucks purchase, enough points for a free coffee.

Delta already has partnerships that allow its customers to accrue SkyMiles, namely with Lyft, Instacart and Airbnb.

The collaboration will enable consumers to get more out of “two of the country’s most celebrated loyalty programs,” said Ryan Butz, vice president of loyalty and marketing at Starbucks.