A U.S. appeals court upheld a major antitrust ruling against Google, siding with Epic Games and ordering sweeping Play Store reforms to boost app market competition.

The court rejected Google’s argument that the trial judge made legal errors in the antitrust case that unfairly favored Epic Games.

A federal appeals court has upheld a jury verdict condemning Google’s Android app store as an illegal monopoly, clearing the way for a judge to enforce a potentially disruptive shakeup.