In yet another sign that the launch of Apple‘s long-rumored iWatch may be imminent, the company has reportedly updated its privacy policy for how health apps handle user data.

Apple recently changed its guidelines for developers who wants to take advantage of its HealthKit framework, according to the Financial Times.

HealthKit, which will debut alongside iOS 8, serves as a hub for health data collected by third-party fitness and health-tracking apps. That information will then be funneled into Apple’s Health App, which will analyze the data, and break it down into easily digestible formats.

The new rules state that developers can’t “sell an end-user’s health information collected through the HealthKit API to advertising platforms, data brokers or information resellers,” according to the report. What’s more, developers cannot use HealthKit’s API or its information “for any purpose other than providing health and/or fitness services.”

It’s been rumored that HealthKit and the consumer-facing Health app will play a big role in the upcoming iWatch, so it makes sense that Apple would want to lock down its privacy policies ahead of the launch, which many think will be held on Sept. 9. Previous reports suggested that the iWatch will be able to track users’ calories and blood sugar, as well as sleep and blood-oxygen data.

As fitness trackers like Fitbit and Jawbone grow in popularity, health- and fitness-focused apps have also been on the rise. Mobile analytics company Flurry reported in June that these apps were growing 87% faster than any other app.

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