In a first of its kind move, Europe’s antitrust regulators on Wednesday levied a fine against Microsoft for breaking a settlement agreement. The $732M sanction against the tech giant came after the competition authority was tipped off that Microsoft had failed to comply with an earlier promise to provide buyers of new computers in Europe the option to opt out of its built-in Internet Explorer browser. Among the companies that first complained to the EU about Microsoft’s non-complicance was arch-rival Google, The Financial Times reported. The EU’s hard line against Microsoft is seen as a warning shot that it is serious about enforcing other antitrust settlements. And, since Google is involved in its own negotiations with European regulators over their concerns about how it runs its search and advertising business, the precedent-setting Microsoft settlement could come back to haunt it.

“It’s important for the Commission to show it’s serious in this case because this will set a precedent, and because the commission increasingly uses settlements to help reach solutions more quickly, especially in the fast-moving technology sector,” Nicolas Petit, a professor of competition law and economics at the University of Liège, told The New York Times. According to the FT, Joaquín Almunia, the European Union competition commissioner, made an indirect reference to the talks with Google when he said he’d asked his staff “to be extremely careful about how we design the monitoring and compliance” provisions of antitrust pacts.

Microsoft for its part has complained about Google’s practices to Almunia, the NYT said. It’s also been running the Scroogled campaign to lure customers to its Bing and Outlook services by telling them Google is reading their emails. In a statement on Wednesday, Microsoft said, “We take full responsibility for the technical error that caused this problem and have apologized. We have taken steps to strengthen our software development and other processes to help avoid this mistake — or anything similar — in the future.”