Microsoft is giving a free upgrade to Windows 10 for users running pirated Windows 7 or 8.1. But there’s a hidden catch that somewhat undermines the exercise.

Earlier this week Microsoft announced at a conference in China that the free upgrade that’s being offered to almost all Windows 7 and 8.1 users will apply even if the user’s copy is unlicensed. It appeared initially this was a special measure just for China, where statistics suggest piracy is so rife that it’s almost a cultural oddity to have paid for Windows.

Painful as such a move might have felt to Microsoft, it made sense on the surface. Making money from Windows sales is becoming less and less important, so it’s better to get as many people using the new system as possible to expand the audience for app sales.

The way Microsoft initially explained the move also had security benefits. Not having to worry about licensing and authenticity checks might make users more likely to set their machines to automatically install security updates from Microsoft. It would also give them less incentive to visit sites relating to pirated software — sites that often pose a security risk.

However, Microsoft has now clarified the change of policy. Firstly, it will apply worldwide, not just in China. That makes it tougher from a PR perspective as it ‘rewards’ pirates even in countries where paying large amounts for Windows (whether directly or through higher PC prices) is more commonplace.

Secondly, Microsoft has now explained that even though you can get the official upgrade from pirated Windows 7 or 8.1 to Windows 10 without charge, the copy of Windows 10 you get won’t be licensed or considered genuine.

The company hasn’t confirmed exactly what practical difference that will make to users. If it’s anything like previous editions, there’ll be frequent nagging messages warning the user they are running a non-genuine copy, and the desktop will turn black every 60 minutes. It’s also likely the only updates the user will get will be security patches ranked as critical.

The problem there is it’s already established that you’re dealing with people who are reluctant at best to pay for software and are willing to look to unofficial sources to get it. Chances are a lot of existing pirates will simply decide it’s better to get a knock-off copy of Windows 10 elsewhere, specifically one that’s already been modified to bypass the warning messages and lack of updates.

Let’s be honest: if Windows 10 is any good, most pirates would be finding a way to help themselves to a free upgrade anyway. Microsoft could have chosen either continuing to take the hardest possible line with pirates, or to bite the bullet and take away any excuse they had not to go totally legit. Instead it’s chosen a middle ground that achieves neither aim.