What just happened? We’re used to seeing big tech companies throwing patent infringement lawsuits at each other—Apple and Samsung have been doing it for years—but BlackBerry and Facebook were two unlikely rivals that headed to the courts last March when the one-time phone giant sued the social network. Now, Facebook is returning the favor with a lawsuit of its own.

In BlackBerry’s lawsuit against Facebook and its WhatsApp and Instagram subsidiaries earlier this year, the company claimed they had copied technology and features from its own BlackBerry Messenger service.

According to Bloomberg, Facebook has just filed a 118-page complaint in San Francisco federal court that accuses BlackBerry of infringing on its patented processes, which includes its voice messaging technology. The social network is seeking unspecified damages for infringement of six of its patents.

Other patents that Facebook claims BlackBerry is improperly using includes technology for improving graphics, video, and audio on mobile devices, along with one “that centralizes tracking and analysis of GPS data.”

With over 40,000 global patents related to technology, BlackBerry has attempted to make other companies pay royalties for using these patents—part of its money-making strategy. Qualcomm agreed to pay it $940 million in royalty refunds last year, and in February 2017, BlackBerry sued Nokia over alleged infringement of its 3G and 4G wireless technology.

BlackBerry licensed its brand to TCL back in 2016; a deal that allows the Chinese electronics giant to design, build, sell, and support all future BlackBerry handsets. A cheaper version of the BlackBerry Key2—the Key2 LE—was on show at IFA. Check out our picks from the event here.