Like many of the high-end flagships we’ve seen this year, the HTC One M9 boasts the latest Gorilla Glass 4 from Corning. But according to one leaker, some units are being shipped with Gorilla Glass 3 instead.

Gorilla Glass 4 is around twice as tough as its predecessor, which means smartphones that carry it are less likely to shatter when you drop them. Some Galaxy S6 drop tests have already proven that it’s surprisingly robust — even on the curved S6 edge.

HTC announced that its new One M9 and One M9+ would come with Gorilla Glass 4 displays, but according to ever-reliable leaker @Upleaks, not every model the Taiwanese company ships has it. Some are shipping with Gorilla Glass 3 instead.

@Upleaks provides a photo of an internal document, thought to be distributed among HTC service representatives, that allegedly reads: “M9 has Gorilla Glass 3 (some lots have 4th gen), not recommended to talk with customer about M9+’s glass.”

We can’t confirm this, unfortunately, because no one on the Cult of Android team can read Chinese. There’s no guarantee this really is an HTC document, either. But given @Upleaks’ track record, we have no reason to doubt its authenticity.

It’s not unheard of for manufacturers to use different components when necessary, and as long as they’re comparable, there shouldn’t be a problem. Recent reports have revealed how Samsung is using two different cameras for the Galaxy S6 and S6 edge, for instance — one of which it makes in-house, and another from Sony.

But if HTC promised Gorilla Glass 4, it should really be delivering it. Would you be upset if you found out your One M9 had older Gorilla Glass?

• SourceUpleaks