When Google first unveiled the new Android Marshmallow, one of the very first to adopt the new platform was HTC, releasing its One A9 flagship with Android 6.0 right out of the box. HTC then promised that follow-up updates to Android M will get to the rest of the flagships at least 90 days from when Google rolled out its updates to the Nexus lineups.

HTC seems to have made good on its promise as reports of an Android 6.0.1 update to the One A9 have floated online. In addition, HTC also started updating the unlocked version of the One M9 to Android 6.0.

According to Gadgets 360, the rollout started with an announcement from HTC's vice-president of Product Management Mo Versi. Versi tweeted "Happy Holidays! Updates to the Unlocked A9 6.0.1 and Unlocked M9 6.0 will be able to be downloaded within next 24 hours!"

Phone Arena added that the rollout is taking shape, and the industry follower has proof that indeed, the Android M update releases to both flagships are currently ongoing. The industry observer noted that for the One M9, the Android Marshmallow jump comes in two stages. Apparently, users of the unlocked version will receive two OTA notifications -– the first one, coming in at 99.47 MB, prepares the phone for the Android M update. The 6.0 version build itself comes next, and is also the larger of the two, coming in as a 1.21-GB download.

The major Android M update brings a number of improvements and fixes for the One M9, including the new battery-saving feature called Doze. There are also changes to app permissions that give users freedom to control which features they can turn on in connection to their apps. Meanwhile, the Android 6.0.1 update on the One A9 unlocks minor fixes and improvements to the HTC flagship.