Having run ./configure --help there is a list of options that can be tweaked in the future build, for example --enable-luajit Enable LuaJit Support --disable-env clearing/setting of ENV vars Though any option can be used with enable and disable prefix, some are presented as --enable-me and other as --disable-me in the help output. Is this supposed to hint me of default values, and if yes, how do I to figure them out? Because either way makes sense to me: luajit is disabled by default and therefore it is presented as --enable-luajit so I can enable it by conveniently copy-pasting it from help output to command line. being listed with --enable in help output indicates that luajit is enabled by default.