Thanks I'd hoped this would do the trick (but didn't):   Func SetupGecko() $ff = '--binary C:\Program Files (x86)\Mozilla Firefox\firefox.exe' _WDOption('Driver', 'geckodriver') _WDOption('DriverParams', $ff) _WDOption('Port', 2828) $sDesiredCapabilities = '{"desiredCapabilities":{"javascriptEnabled":true,"nativeEvents":true,"acceptInsecureCerts":true}}' EndFunc