Microsoft is moving its Edge Windows browser to Google’s open source Chromium rendering engine. The move will mean Edge will be far more compatible with websites, but Microsoft will also be able to contribute to the underlying code of the Chrome browser and ensure it improves on Windows 10. Google has welcomed Microsoft’s move in a statement to The Verge.

“Chrome has been a champion of the open web since inception and we welcome Microsoft to the community of Chromium contributors,” says a Google spokesperson. “We look forward to working with Microsoft and the web standards community to advance the open web, support user choice and deliver great browsing experiences.”

While Google is welcoming the move, Mozilla isn’t at all. “This just increases the importance of Mozilla’s role as the only independent choice,” says a Mozilla spokesperson in a statement to VentureBeat. “We are not going to concede that Google’s implementation of the web is the only option consumers should have. That’s why we built Firefox in the first place and why we will always fight for a truly open web.”

While Microsoft and Google seem to be aligned, it’s still not clear whether Google will create a Windows Store version of Chrome. Microsoft continues to have policies that restrict store apps to its own rendering engine, which will now be Chromium-based in the future. As it stands, Windows 10 devices running in S Mode cannot install Chrome unless S Mode is disabled as it’s not available in the Windows Store. Microsoft and Google probably have some more making up to do until we ever see a version of Chrome in the Windows Store.

Update, 2:40PM ET December 6th: Article updated with Mozilla comment.