Last week, AT&T launched a new loyalty program dubbed AT&T Thanks, offering rewards to customers, especially those who bundle together wireless and pay-TV services from the company. This morning, Citi fired back at the Death Star, alleging that AT&T is stomping all over Citi’s “ThankYou” trademark.

For several years, Citi has had trademarks protecting its “ThankYou from Citi” credit card rewards program, while AT&T more recently filed with the U.S. Patent and Trademark Office for its “AT&T Thanks” mark.

That AT&T mark was published for opposition this week, and it looks like Citi has a problem with it. Citi has sued the telecom titan this morning in federal court seeking to block continued infringement of its trademark, along with damages.

While Citi has registered multiple variations of its “ThankYou” mark, we couldn’t find anything indicating that the bank has registered anything that that says “Thanks.”

Both the Thanks and ThankYou programs do involve loyalty rewards, though the ThankYou mark is more explicitly designated to cover credit and debit card rewards while the AT&T Thanks doesn’t make any mention of specific types of products or commerce; just “incentive rewards programs for customers for the purpose of promoting and rewarding loyalty.”

According to the complaint [PDF] Citi is concerned about confusion of, among other things, credit cards that are co-branded by AT&T.

For nearly 20 years, Citigroup and AT&T have issued co-branded credit cards, including the AT&T Universal Card and the AT&T Access Card. According to Citi, around 1.7 million customers currently have one of these cards.

“As a result of Citigroup and AT&T’s partnership and co-branding efforts and the marketing efforts associated therewith, consumers are accustomed to seeing the Citigroup and AT&T names and trademarks together and are familiar with the association between these two companies,” reads the complaint, later adding that “the likelihood of consumer confusion or mistake or deception is exacerbated by Citigroup and AT&T’s history of co-branding credit cards and services and the use of Citigroup’s THANKYOU marks in connection with those co-branded credit cards and services.”

The bank says it made AT&T aware of its concerns in April 2016, but that the telecom company went ahead and launched the Thanks program while discussions were ongoing.

We’ve reached out to AT&T for comment, but have not yet heard back from the company.

[via Reuters]