audioOS 9.9.13.3 (build 17C54) is an official Apple over-the-air update for the HomePod, released on 2019-12-10T18:21:47Z. The update package is 934.93 MB. This is a delta (partial) update that requires 12.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 6660969731d1319094e004a57b56da647cdab61c.zip.