From one budget airline to another.

After Spirit Airlines shut down, many budget travelers were left scrambling, leaving many passengers to look for last-minute alternatives and even leaving one airport with no commercial flights at all.

Many airlines — and weirdly enough, Papa John’s — have been stepping in to help those stranded travelers.

Frontier Airlines is extending its support to former Spirit customers with new offers and rewards, and its existing loyal customers can take advantage, too.

For a limited time, Frontier is waiving the $50 enrollment fee to join the airline’s low-fare club, Discount Den.

From now through Friday, May 15, customers can join Discount Den for just the $59.99 annual membership cost, providing a $50 savings and allowing members to affordably replan their interrupted travel plans, as well as earn miles and Elite Status Points in the process.

New and current Discount Den members will also be rewarded with a $25 voucher for recruiting friends and family to join Discount Den. Their Frontier Miles membership number will serve as their unique referral code.

Additionally, the value airline launched “Fly One, Get One,” where qualifying Frontier Miles members can earn 5,000 extra miles for each round trip flown through August 31, on up to four round trips total, or 20,000 miles. That’s enough for four one-way domestic award flights.

Joining the Frontier Miles program is completely free, and these extra miles on top of the standard miles travelers already earn for every dollar spent, based on Elite Status level, will allow them “to rebuild miles they lost with Spirit’s operations ending,” the airline said.

To take part in the promotion, members must opt in on Frontier’s website before booking and at least 24 hours prior to departure.

“We recognize the challenges consumers are currently facing as they navigate the cancellation of their planned travel, and we are pleased to offer affordable alternatives and valuable loyalty rewards as they replan with Frontier,” Bobby Schroeter, Chief Commercial Officer, Frontier Airlines, said in a statement.

“With our signature low fares and one of the most rewarding loyalty programs in the sky, we look forward to showing consumers why they should make us their new airline of choice.”

These new offers come in addition to Frontier’s recently announced rescue fares, which help customers keep access to affordable travel with up to 50% off base fares when booking before May 15 using promo code “SAVENOW.” Flights must be taken by November 19.