Instructions to update the Unifying firmware on Windows
Download and install Unifying Software < http://support.logitech.com/en_us/software/unifying >
To check the firmware version on your Unifying receiver, go to Unifying Software → Advanced, and then select the Unifying Receiver.
The version of the firmware is listed in the right pane.
If the firmware version is in 012.xxx.000xx format, download and save RQR_012_007_00029.exe through the following link: http://chilp.it/3465237
If the firmware version is in 024.xxx.000xx format, download and save RQR_024_005_00029.exe through the following link: http://chilp.it/d49ff27
Run the downloaded firmware package.
Open Unifying Software → Advanced, then select the Unifying Receiver.
In the right pane, click on Update Firmware and wait until the firmware update is complete.