Currently on non-Mac platform, firefox will decompression the content while loading resource with MIME type "application/mac-binhex40". This introduces the confusion like bug 1390708 when Firefox trying to decode BinHex file. On Mac platform we already disabled stream decoding of BinHex file. I tested with Google Chrome 61, Internet Explorer 11, and Safari 11. All these browsers treat BinHex file as binary file and trigger file download directly. I intent to remove all the code that handling BinHex decoding, i.e. nsBinHex.cpp, from mozilla-central if no other project is using it. This will happen on Firefox 58 if no objection on mailing list and in bug 1390708. Best Regards, Shih-Chiang Chien Mozilla Taiwan