The chain formerly known as Kentucky Fried Chicken has sued its competitor for the recent use of the term “Original Recipe” in promotions. KFC has used “Original Recipe” for more than 50 years to describe its blend of 11 herbs and spices.

It’s so closely associated with the term that it trademarked the phrase in 1984.

Church’s, though, began a promotion for its fried chicken in late September that included the phrase “our original recipe is back,” according to the suit. KFC officials sent a letter on Oct. 24 to protest the use of the phrase, but that didn’t stop Church’s. Now, the two are going to court.

“On behalf of all fried chicken lovers out there, we take it personally when another company tries to claim our iconic taste and branding as their own,” a KFC spokesperson told Reuters. “We remain committed to protecting our brand’s intellectual property and safeguarding the experience of our customers.”

Church’s declined to comment, citing active litigation.

At issue, says KFC, is confusion among consumers, who it says have associated the phrase “Original Recipe” with its chain. The suit claims Church’s is “causing irreparable harm” to KFC by using the two-word descriptor.

KFC is asking the court to order Church’s to stop using the phrase, eliminate all existing ads that use it and for unspecified damages, including attorney’s fees.

The suit comes soon after KFC’s parent company Yum Brands reported an earnings miss on Nov. 5, noting that same-store sales at KFC were down 4% year over year globally and fell 5% in the U.S. Popeyes overtook KFC as the nation’s second largest chicken chain last year.