If it had happened on 1st April nobody would have believed it - but Microsoft has posted its first piece of open source-approved software.
The software giant has released the Windows Installer XML (WiX) toolset, which builds Windows installation packages from XML source code, to SourceForge.net, the open source developer community.
The project, originally developed within Microsoft, was released under the Common Public Licence, an externally created open source licence.
With this release, developers outside Microsoft can take advantage of the same toolset that is used to create installation packages (MSI and MSM files) for Microsoft products such as Office and SQL Server.
Internal Microsoft teams working on products such as Office, SQL Server, BizTalk, Virtual PC and Instant Messenger use WiX to build their MSI and MSM files today.
A Microsoft spokeswoman told vnunet.com: "Microsoft is committed to providing the tools for developers to be successful.
"Many SourceForge projects are based on Windows. The WiX technology will be beneficial to a broad array of project developers as they seek to build better Windows software."
On his website, Microsoft developer Rob Mensching, who worked on the tool in his free time and drove the release, explained that the open source move was the result of "many people's efforts to improve Microsoft from the inside out".
"I'm not exactly sure what is going to happen next but I'm sure there are quite a few people who are interested to see where this leads," he said.
"Personally, all I hope is that if you find WiX useful then you'll join the community and help us improve the toolset."
Cotton seedling freezes to death as Chang'e-4 shuts down for the Moon's 14-day lunar night
Fortnite easily out-earns PUBG, Assassin's Creed Odyssey and Red Dead Redemption 2 in 2018
Meteor showers as a service will be visible for about 100 kilometres in all directions
Saturn's rings only formed in the past 100 million years, suggests analysis of Cassini space probe data
New findings contradict conventional belief that Saturn's rings were formed along with the planet about 4.5 billion years ago