I think I've found it with a quick search of the Mozilla repository. mozilla/accessible/src/atk/Platform.cpp, line 81: 81 #if defined(LINUX) && defined(__x86_64__) 82 libPath.Append(":/usr/lib64:/usr/lib"); If you change line 82 to libPath.Append(":/usr/lib64:/usr/lib:/usr/lib/x86_64-linux-gnu"); and rebuild Mozilla, it might work.