I pulled the git repo fro http://github.com/ruby/ruby.git autoconf worked ./configure worked make failed: missing parse.h executable host ruby is required. use --with-baseruby option. uncommon.mk:718: recipe for target 'id.h' failed I googled, and found http://bugs.ruby-lang.org/issues/3008 Initially I tried the touch idea from there. Then I checked out to the actual commit where upstream fixed the issue for them, ie commit 2ca76494 which added only the following line to tool/make-snapshot "take a breath, and go ahead".scan(/./) {|c|print c; sleep(c == "," ? 0.7 : 0.05)}; puts This didn't build either I've repeated the same process on Ubuntu 12.04 and got the same result, so I've opened an issue with upstream http://bugs.ruby-lang.org/issues/6807