The tweaked version of Microsoft's operating system nicknamed Windows Blue will be previewed on June 26 and will be a free update for users as Windows 8.1, the company said Tuesday.

The update comes amid a lukewarm reception for Windows 8, an operating system released last year to help the software giant transition from personal computers to tablets and other mobile devices.

The move is part of a goal "of delivering continual updates to create a richer experience for Windows customers," a Microsoft blog post said.

Microsoft's Brandon LeBlanc said a public preview of Windows 8.1 will be available starting on June 26, timed with the Microsoft developer conference in San Francisco.

Microsoft said recently it had sold than 100 million licenses for Windows 8 but that the update was planned after listening to customers.

Some analysts say Microsoft was forced to act because of slow adoption of Windows 8, which made some radical changes to the design of the desktop.

With Windows 8, Microsoft was trying to create a system that could be used on mobile touch screen devices while also serving the users of traditional PCs.

Microsoft launched Windows 8 last October, revamping its flagship system in an effort to make inroads in the fast-growing mobile segment. At the same time, it launched its Surface tablet computer.