Not the current one, but Windows 10, indicating that a sea change might be happening in the mobile market.
Xiaomi is the latest to sign up to the Microsoft vision and at least agreed to test the new software. Xiaomi is important because it has catapulted themselves into the mainstream and have even displaced companies such as Samsung in China.
It is believed that the company potentially release a Windows 10 smartphone later this year.
According to Microsoft, Xiaomi is testing out Windows 10 on the Xiaomi Mi 4 smartphone and that a select group of Mi 4 owners will be chosen to help test Windows 10 on the device.
The Mi 4 was launched in the middle of last year and it is rather good – cheap with some decent specs.
Some have suggested that the Mi 4 could actually even be a dual boot thing running on Android and Windows 10, although we can't really see the point of doing that.