You never needed a Add-On. I have no idea why someone would make one and it is allowed as a download. Just needed to go here : http://www.speedtest.net/ I suggest posting your issues on Internet Speed Test's Support Page https://github.com/ray-lothian/internet-speed-test/issues Has the Home Page setting been changed under Tools --> Options ? Also this is Internet Speed Test Add-On for sure the name is right ? As there are several variations of the name and several diff Add-Ons as per https://www.google.ca/search?q=internet+speed+test+firefox+add-on&ie=utf-8&oe=utf-8&gws_rd=cr&dcr=0&ei=cB7KWfDqJceJ0gLh0JK4DQ Also there is a virus/malware version out as per here : https://www.google.ca/search?q=manually+remove+internet+speed+test+firefox+add-on&ie=utf-8&oe=utf-8&gws_rd=cr&dcr=0&ei=RR_KWb_-LYmO0gKjz6-ACQ So can you please report back with name and the link if possible from the download. Also if get any reply from their Support Page. Please let us know if this solved your issue or if need further assistance.