Apple is striking back at Koss, which filed a patent infringement lawsuit last month related to AirPods and Beats. It countersued the maker of the first stereo headphones, asking for a court to rule that Apple didn’t infringe any of the five patents as laid out in the original suit. Not only that, it contends Koss didn’t have the right to sue over wireless headphone tech in the first place.

Koss met with Apple multiple times under a confidentiality agreement, according to Patently Apple. While Apple was seemingly happy to have no restrictions on the discussions, Koss is said to have insisted on the agreement. It prevents either side from litigating based on anything they discovered in the talks. But Apple claims that’s “exactly what Koss did.”