I am trying to get firefox to invoke a custom program when it encounters a magnet url. I have added the protocol(HKEY_CLASSES_ROOT > magnet > shell > open > command) with regedit. It appears to be added correctly, since Chrome is able to understand it without further configuration. I have tried adding the network.protocol-handler.expose.magnet boolean key in about:config in firefox. Neither having it set to false nor true changes anything. The error i am getting is along the lines with "firefox does not know how to open the magnet protocol since it is not associated with any program"(My message is not in english so no exact translation). Also, no mention of magnet shows up under Programs in the firefox settings. My Firefox version is 17.0.1 The program association i set in regedit is "E:\Program\Python27\pythonw.exe" "E:\Program\Misc\magnet_add.pyw" "%1" Thanks in advance for your help