Thanks to Google, Microsoft is set to pay a nearly $750 million fine to the European Union after violating an antitrust law.

On Wednesday, the New York Times reported that the European Union will fine Microsoft for $732 million for reneging on an agreement it made with EU antitrust regulators to make it easier for Windows customers to use competing Web browsers. Later in the day, the Wall Street Journal noted that the EU only levied the fine after the error was pointed out by a “third party.” The report speculated that Google was that third party. Then, later in the day, FT confirmed that Google was indeed behind the leak.

Joaquin Almunia, the European Union’s competition commissioner, claimed that Microsoft was in violation of the EU’s antitrust laws due to how it bundled Internet Explorer with every copy of Windows. Originally, Microsoft was told it had to offer consumers a choice between different browsers when they first set up a new Windows-based computer. However, after initially agreeing to comply with the order, Microsoft quickly abandoned the agreement , which led to the violation. Curiously, the EU only noticed the slipup when it was notified by Google.

Microsoft has already taken responsibility for the incident, though spokespeople refused to speculate on whether or not Google had reported the company.

“We take full responsibility for the technical error that caused this problem and have apologized,” Microsoft told the New York Times. “We have taken steps to strengthen our software development and other processes to help avoid this mistake -- or anything similar -- in the future.”

While Google almost undoubtedly ratted out Microsoft to increase the market share for its Chrome Web browser, FT notes that the whole affair might come back to bite Google in the end.

“This is a double-edged victory for Google, however, given it is in the later stages of its own EU settlement negotiations,” FT reported. “Microsoft’s lapse, which went unnoticed for more than a year, is prompting [regulators] to consider putting more rigorous monitoring conditions in future deals.”