Apple has released an updated build of iOS 8.4.1 for registered developers to test on iPhone, iPad, and iPod touch. iOS 8.4.1 beta 2 features build number 12H318 and comes just over two weeks after the initial beta version.

While the initial beta of iOS 8.4.1 didn’t feature any noticeable changes, the X.X.1 label suggests it is primarily an under-the-hood update to iOS 8.4 without feature or visual changes. iOS 8.4 launched in late June and introduced Apple Music with Beats 1 to the iPhone, iPad, and iPod touch.

iOS 8.4 also delivered a number of other changes including an iBooks app for CarPlay that supports audiobook playback, iBooks Author and textbook support on iPhone, and more.

The latest iOS 8.4.1 build is rolling out as an over-the-air update through the Software Updates section of the Settings app. The software update will likely hit Apple’s Developer Center as well, although only the previous build is currently available for download.

Registered developers will need to download the initial build, then update OTA to the second iOS 8.4.1 beta to test the operating system update. Many developers are focused on testing and developing for the upcoming iOS 9 release scheduled to debut this fall. Apple released the fourth beta version of iOS 9 for registered developers just over a week ago.