Sony Mobile has started to roll a minor update for the LTE Xperia M2 variants (D2303, D2306), which moves the build number from 18.3.1.C.1.15 to version 18.3.1.C.1.16. The phone remains on Android 4.4.4 KitKat, but is due an update to Android 5.1 Lollipop later this year.
Update: The firmware update has also landed on the Xperia M4 Aqua (D2403).
DOWNLOAD FTF:
Xperia M2 (D2303) Central Europe 1 Generic – 18.3.1.C.1.16
Xperia M2 Aqua (D2403) Central Europe 1 Generic – 18.3.1.C.1.16
Thanks Sergio!