A German antitrust watchdog ruled Thursday that Facebook must stop collecting some data without users’ consent.

The Federal Cartel Office, known as the Bundeskartellamt, published its findings after a three-year investigation.

It ruled that Facebook will no longer be able to freely collect data from third-party services and websites and merge that data with Facebook’s users' profiles — a practice that allows it to create a much more attractive product for advertisers.

Facebook says it will appeal the decision, accusing the German watchdog of unfairly targeting the tech giant.

Currently, Facebook collects data from services such as its own WhatsApp messaging platform and the Instagram photo-sharing app, as well as third-party websites that install Facebook’s own Like and Share buttons.