I know what you’re thinking. SR1? Seriously? But it’s true: just a week after the initial release of Windows 10, Microsoft has delivered the first major update to its latest OS. Dubbed Service Release 1 (SR1) internally, this cumulative update for Windows 10 provides no new features but does offer a ton of small fixes.

“This update includes non–security-related changes to enhance the functionality of Windows 10 through new features and improvements, the Knowledge Base article for this update blandly notes. “Windows 10 updates are cumulative. Therefore, this package contains all previously-released fixes (see KB 3074683). If you have installed previous updates, only the new fixes that are contained in this package will be downloaded and installed to your computer.”

While this is certainly a large update, weighing in at about 325 MB, it is of course not the first update to Windows 10: Microsoft has been issuing fixes and other updates for the system since it sort-of-not-really-wink-wink RTM’d last month. But it’s also not clear exactly what’s in this update, despite a long change list on the KB page.

Regardless, this will be the first taste of Microsoft’s “rapid release” vision for many. And it does require a reboot, so plan accordingly.

You can find the update—called Cumulative Update for Windows 10 (KB3081424)—in Windows Update.