Report Poseidon Z driver for Mac OS X 10.10+ in Mechanical Posted April 7, 2015 After following all the steps (0-4), my Poseidon Z keyboard finally works! I would just like to add that I had to restart my iMac in order for the terminal command to work. And the keyboard was finally functioning properly after I restarted my computer in step 4. Excellent job on fixing this issue. You saved me 700 HKD, since I don't have a Windows computer of my own.