User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-GB; rv:220.127.116.11) Gecko/2008120122 Firefox/3.0.5 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-GB; rv:18.104.22.168) Gecko/2008120122 Firefox/3.0.5 Even when browser.fixup.alternate.enabled is set to true, it should never apply the fixup to "localhost". Nobody *ever* typed "localhost" when they really wanted "www.localhost.com". Reproducible: Always Steps to Reproduce: Fetch a "broken" local web application using the URL "http://localhost/myapp/index.php" Actual Results: After the "broken" page errors, Firefox redirects to the URL "http://www.localhost.com/myapp/index.php". Expected Results: Firefox should have given me a "page load error" for "localhost", not one for www.localhost.com The "fixup" should not apply to "localhost". This site should be treated as a special case.