Even though it currently sells three main iPhone generations, as well as the lower-end SE, not to mention three types of iPads with four different screen sizes, Apple unexpectedly retired its Series 2 smartwatch unveiled last year on the heels of the Series 3 announcement.

The Apple Watch Series 1 is still around, but despite what the name suggests, that’s not actually the “original gangsta.” The first-gen Apple Watch, packing a single-core S1 SoC, was confusingly replaced with a dual-core S1P-powered variant in fall of 2016.

Now, there’s nothing wrong with continuing to own the OG “iWatch” if you don’t need stuff like built-in GPS, full water protection, decent battery life or standalone cellular connectivity.

But as early 2015 hardware starts to degrade, so will the accompanying software. Cupertino is yet to leave the pioneering Apple Watch generation behind in terms of major updates, though some hot new features are seemingly not supported.

For the most part, watchOS 4 should work just fine regardless of your wearable product’s age. Activity tracking is vastly improved, workouts are more precise and easier to personalize, while heart rate monitoring is… largely the same. Wait, what?

Yup, we’re sorry to report that the “enhanced” Heart Rate app in watchOS 4 is… unenhanced on the original Apple Watch. No resting, walking or recovery HR readings for you. Just the old “current” heart rate status. Oh, and no alerts for elevated numbers either, it seems.

Many disgruntled users have been quick to point out competing wearable devices, like entry-level Fitbits, can monitor resting heart rate with presumably humbler internal equipment than the Apple Watch… Series 0.

Maybe, just maybe a future OS update will activate the in-depth HR supervision on the oldest piece of wrist-worn iGear, and this is not an S1 processor limitation after all. But for now, it’s at the very least an annoying omission.