It’s going to get harder for Android apps to track users who’ve opted out of receiving personalized ads, the Financial Times reports, after Google announced changes to how it’ll handle the unique device identifiers that allow marketers to track them between apps. Starting later this year, Google is cutting off access to these “Advertising IDs” after a user opts out, and will show developers a “string of zeros” in its place.

The news was announced in an email to Play Store developers, and Google has also updated its support page for Advertising IDs with the announcement. Google told developers the changes will “provide users with more control over their data, and help bolster security and privacy,” the Financial Times reports.

The change comes a few short months after Apple overhauled how advertising IDs work on iOS in an apparent attempt to compete with the new policy. Recently, Google also announced that it’s adding privacy info to its Play Store listings, mirroring a similar feature Apple added to its App Store last year, and is also limiting which apps can see what you have installed on your phone.

Users have long been able to opt out of personalized ads on Android (you can do so by heading into the Settings app, going into the Google menu, and selecting “Ads”), but it seems this doesn’t currently stop developers from being able to access your device’s advertising ID entirely. AdExchanger reports that apps have previously been able to use the identifier for non-advertising purposes like analytics and fraud prevention, and Google’s support page says it will announce an “alternate solution” for these use cases next month.

Google’s support page says that the rollout of the new policy will happen in phases. Android 12 devices will start seeing the change in “late 2021,” before it rolls out to all devices with Google Play early next year. XDA Developers reports that Google Play Services will also notify existing apps with access to your advertising ID and related data, so that this can be deleted where appropriate.

Although Google’s announcement follows hot on the heels of Apple’s own ad tracking changes, it’s not yet clear how similar the two approaches will be. Google’s support page still refers to the decision to stop ad tracking as an “opt out” process, while Apple’s changes effectively make tracking an opt-in decision. But regardless of how Google eventually handles the process, it’s another potentially huge shake-up for the digital advertising industry.