Apple quietly updated its App Store guidelines on Monday, while the keynote address of WWDC was happening in San Jose, to allow for mobile apps like Valve’s Steam Link game streaming service, according to Reuters. Steam owner Valve said last week Apple had initially rejected Steam Link, which lets consumers access and stream their PC game library onto a mobile device, due to apparent “business” conflicts.

The change does not void Apple’s long-standing policy that no iOS app may host an app store of its own and allow users to purchase and download software not approved through its own marketplace. Apple does that because it likes to keep tight control over the type of content allowed on iOS devices, and also because it has since the advent of the App Store typically taken 30 percent of all revenue. (In 2016, Apple adjusted that policy to let developers keep an additional 15 percent of in-app revenue for subscription services, so long as a user was subscribed for at least 12 months.) Apple’s growing services business, which includes the App Store, is a pillar of its evolving business model, so it makes sense that Apple would prevent any app that tries to undermine that.

The new rule does, however, allow for what are known as remote mirroring apps, like Steam Link, to contain an app store so long as purchases through that app store are processed on the desktop PC, and not on the iPhone or iPad itself. This seems like a relatively straightforward exemption, and it opens the door for apps like Steam Link and other game streaming services to work on iOS devices. There’s no word yet on the availability of Steam Link in the App Store — presumably, Valve must resubmit it — though the app is already in open beta on Android.