Microsoft can’t seem to get Windows 10 Redstone 4 (RS4) out the door, but it has no problem releasing new RS5 builds. Today, it released yet another RS5 build to those Windows Insiders who have opted into Skip Ahead.

There are only two big new features in this new build, 17650: A Fluent Design System refresh for Windows Defender Security Center and Windows Defender Firewall support for Windows Subsystem for Linux (WSL) processes.

The first of those is just a visual refresh: Windows Defender Security Center now sports the Acrylic translucency effect and Reveal Highlights when you mouse over interactive on-screen elements.

“We’ve adjusted the spacing and padding around the app and will now dynamically size the categories on the main page if more room is needed for extra info,” Microsoft notes. “We’ve also updated the title bar of the app so that it will now use your accent color if you’ve enabled that option in Color Settings.”

The second update is a bit more technical: Now you can add specific rules for Windows Subsystem for Linux (WSL) processes to the Windows Defender firewall, just as you can for normal Windows processes.

“Also, Windows Defender Firewall now supports notifications for WSL processes, Microsoft explains. “For example, when a Linux tool wants to allow access to a port from the outside (like SSH or a web server like nginx), the Windows Defender Firewall will prompt to allow access just like it would for a Windows process when the port starts accepting connections.”

There are a number of fixes in this build too, and Microsoft notes several known issues. Check out the original post for more info.