diff --git a/README.md b/README.md
index 1a725ea..a51e51b 100644
--- a/README.md
+++ b/README.md
@@ -15,15 +15,21 @@ What works:
 - Temperature sensors,
 - Battery status,
 - Brightness control,
-- Sound,
+- Audio,
 - USB ports,
 - Graphical acceleration (QE/CI).
 
+## UltraBay HDD
+
+When using HDD in Ultrabay (instead of optical drive): install [AHCIPortInjector.kext](https://www.insanelymac.com/forum/files/file/436-ahciportinjectorkext/) and [AppleAHCIPort.kext](https://www.insanelymac.com/forum/files/file/815-appleahciportkext/) in `/Library/Extensions`.
+
+`AHCIPortInjector.kext` fixes the `Disk not initialized` issue (disk cannot be read). `AppleAHCIPort.kext` fixes the disk being detected as an external drive (instead of internal).
+
 ## HiDPI
 
 For FHD (1920x1080) panels, I recommend to install [One Key HiDPI](https://github.com/xzhih/one-key-hidpi).
 
-## Upgrade High Sierra => Mojave
+## Upgrading from High Sierra to Mojave
 
 Once the upgrade complete, make sure to rebuild the kext cache to fix brightness control issue, by running in Terminal: