HTC will push an Android 6.0 Marshmallow update to a number of its smartphones in the next two quarters, according to frequent Twitter source @LlabTooFer -- like the HTC One M9.

Enlarge Image LLabTooFer

As the most recent version of Android, 6.0 Marshmallow brings a host of new features, like Google Now on Tap and Android Pay for mobile payments. Phone vendors that can update older models to the new operating system quickly can avoid scathing customer complaints that come when phone owners are stuck with the old operating system months after rival phones update.

LLabTooFer's unconfirmed schedule of HTC's updates (above) is not a leaked internal document; instead it's a compilation of rumors from other sources that project when certain phones will receive Android 6.0.

Approached for comment, HTC declined to respond.

Following HTC's past moves, the more recent and more popular devices could see Android 6.0, or maybe even 6.0.1, first. Moreover, the software updates is also expected to deliver newer versions of HTC's custom Sense interface that it lays on top of Android.

The first quarter of 2016 may see the HTC One M9+ and One E8 grabbing an update, followed by various Butterfly and Desire families the following quarter.

If there's one big takeaway from the rumored timeline, it's that the original HTC One, the One M7 from 2013, may not get any Marshmallow love at all. According to the chart, it could top out at Android version 5.0.2 with HTC Sense 6.0, a disappointment for original HTC One owners.

Remember, nothing is official until HTC announces its own plans, and carrier-branded versions of the phones could take longer to release their Android updates.