Microsoft's Windows Phone 7 devices can track users' locations when the camera application is activated, according to a proposed class action filed at a Seattle federal court.
The lawsuit even reckons that the smartphones continue locating users if they've asked for the tracking software to be switched off.
It could be a devastating blow for Microsoft, whose mobile platform has struggled in comparison to dominant iOS and Android devices.
The lawsuit was brought about on behalf of a Windows Phone 7 user, who claims that approximate latitude and longitude are broadcast whenever the camera application is activated.
Apple of my eye
If this all sounds a touch familiar, Apple apparently attempted a similar trick until a pair of developers uncovered location storage files on their iPhones.
However, Apple quickly denied that it was tracking anyone, and instead said that the files were there to help the iPhone quickly find cell towers and Wi-Fi hotspots.
If it proves to be true, the Microsoft rumour could be a bit more disturbing.
The other big concern is that your location data will be used for marketing, in a way that (according to Steve Jobs) Android already does.
Microsoft has declined to comment on the issue, but when they do we'll know exactly which longitude and latitude they're commenting from.