On March 12, customers can get a free small Thin Mints Frosty with any purchase in the mobile app at participating Wendy’s restaurants nationwide, according to the Ohio-based burger chain. The one-day offer can also be redeemed online, Wendy’s said.

This new Frosty drop was perfectly timed for National Girl Scout Cookie season, and now you can snag one for free. In honor of National Girl Scout Day on March 12, Wendy’s is giving away free small Thin Mints Frosty treats with any purchase—exclusively through the Wendy’s app.