Wireless audio specialist Sonos is suing internet giant Google, claiming it has knowingly used its patented technology without paying for it since 2016.

The grievance relates to Google’s portfolio of smart, wireless, networked speakers, now going under the collective brand of Google Home. Sonos says it gave Google access to its patents in 2013 in order to allow Google Play Music to work on the Sonos platform. At the time Google had no competing hardware.

A couple of years later, however, the Chromecast Audio dongle was launched, which promised to connect regular speaker to the internet. Initially, as the Guardian reported, each connected speaker required its own audio source. But within a couple of months Google added a bunch of additional functionality, including multi-room support, which seems to be the first of the patent infringements.

Here are the main patents Sonos claims are being infringed, although there are another 23 not detailed in the suit:

“Google is an important partner with whom we have collaborated successfully for years, including bringing the Google Assistant to the Sonos platform last year,” said Sonos CEO, Patrick Spence. “However, Google has been blatantly and knowingly copying our patented technology in creating its audio products.

“Despite our repeated & extensive efforts over the last few years, Google has not shown any willingness to work with us on a mutually beneficial solution. We’re left with no choice but to litigate in the interest of protecting our inventions, our customers, and the spirit of innovation that’s defined Sonos from the beginning.”

We’re not aware of any public Google response, but even if they have it will just be templated legalese claiming innocence, so let’s just take that as read. Sonos has filed suit in the Central California district court and also asked the International Trade Commission to block the importing of any of the products claimed to infringe the patents into the US. If Google is guilty of any of this it would be well advised to settle quickly as the PR from exploiting such a well-loved tech brand is unlikely to be good.