Microsoft has revised its targets for hitting one billion Windows 10 installations within three years of release.
The company had hoped to realise the landmark by 2018, but says sluggish Windows 10 Mobile performance has prompted reassessment.
Currently, almost a year since the launch, the film has amassed 350 million users.
“Windows 10 is off to the hottest start in history with over 350 million monthly active devices, with record customer satisfaction and engagement,” wrote Windows marketing chief Yusef Medhi.
"We're pleased with our progress to date, but due to the focusing of our phone hardware business, it will take longer than FY18 for us to reach our goal of 1 billion monthly active devices.”
Microsoft’s job will get harder at the end of this month, once the free upgrade period expires.
Until now Microsoft has been offering the upgrade for free to anyone on Windows 7 or Windows 8.1 devices, but it’ll soon become a paid upgrade.
ZDnet points out that Microsoft had a shot at reaching its lofty target, but the serious drop off in Windows Phone sales - a 57% fall year-on-year - put paid to its chances.
Despite Microsoft’s vow there remains a future in its smartphone platform, Windows Phone is now as good as dead.