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.

In honor of National Girl Scout Day on March 12 and St. Patrick's Day on March 17, Wendy's is offering free Thin Mints Frostys and Fries this week, respectively. Customers can grab the deals through the Wendy's app or website.

Once the new Frosty desserts launch this spring, head to your nearest Michigan Wendy's to grab a taste. The fast-food chain features dozens of restaurants throughout the state. Frosty Swirls are a choice of chocolate or vanilla Frosty swirled with a choice of delicious sauce, Wendy's said.

Wendy’s, the popular fast food chain, celebrates National Girl Scout Day with a surprise for all its customers

And what goes better with a Frosty? How about fries? Now through March 17, St. Patrick’s Day, Wendy’s is giving away free fries with a $5 purchase and drink. Again, you’ll need the app to claim the offer. As always, the deals are subject to a location’s participation, USA Today reported.

The Wendy’s Frosty is a perennial favourite on the menu with the beverage traditionally available in classic flavours such as: Chocolate and Vanilla with the likes of limited edition seasonal flavors such as Salted Caramel, Peppermint and Strawberry also hugely popular.

Wendy's announced at its Investor Day last week it will be introducing two new Frosty varieties to its menu this spring.

Related: Fans Say Wendy’s Is ‘On A Roll’ With 'Phenomenal' New Frosty Treats: 'Now We're Talking' To coincide with National Girls Scouts Day, the beloved fast food chain will be giving away free small Thin Mints Frostys all day long on March 12.