A federal judge in San Francisco just handed a big victory to Epic Games in its long-running antitrust challenge to the technology giant’s app store.

Judge James Donato ordered Alphabet’s Google to overhaul its mobile app business to give Android users more options to download apps and to pay for transactions within them, following a jury verdict last year for “Fortnite” maker Epic Games.

Alphabet must lift restrictions that prevent developers from setting up rival marketplaces that compete with its Google Play Store, upending the search giant’s dominance in the lucrative Android app market.

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Donato said at an earlier hearing that he would establish a three-person compliance and technical committee to implement and monitor the injunction.

Google had urged Donato to reject Epic’s proposed reforms, arguing they were costly, overly restrictive and could harm consumer privacy and security. The judge mostly dismissed those arguments during an August hearing.

“You’re going to end up paying something to make the world right after having been found to be a monopolist,” he told Google’s lawyers.

In a separate antitrust case in Washington, U.S. District Judge Amit Mehta on Aug. 5 ruled for the U.S. Justice Department and said Google had illegally monopolized Web search, spending billions to become the internet’s default search engine.

The judge’s decision is likely to accelerate the weakening of app store controls held by tech giants Google and Apple that have been under fire from regulators and lawmakers around the world.