Hi Graeme, We've discovered the cause of ColorHug not working on OS X and Windows. Basically, OS X and Windows require the device to return a full buffer of the size specified in the HID descriptor rather than an arbitrary size. I've patched the client and the firmware and I'll be doing releases at the weekend to fix things. Would there be any chance to lift off the #ifdef / env-var for the next release? I can provide some test firmware if you'd rather test things out yourself. Thanks, Richard.