Microsoft has said it will miss its target of getting its Windows 10 operating system running on more than one billion devices by 2018.
In a statement, it said problems with its smartphone business would delay it hitting the milestone.
The software giant has struggled to find customers for Windows phones in a market dominated by Android and Apple.
Microsoft says Windows 10 is in active use on about 350 million separate devices at present.
Released in July 2015, Windows 10 has been built to act as a unifying platform across desktops, laptops, tablets, smartphones, small embedded systems and the Xbox One games console.
Shortly before the main release of the operating system, Microsoft set itself the target of getting the software on to one billion devices.
However, its plans took a knock soon after when it sacked 7,800 people in its smartphone business and wrote off the entire value of the Nokia phone business it bought in 2014 for $7.2bn (£5.4bn).