Tried to install a gem on Mountain Lion and make couldn't find gcc-4.2: kamil$ gem install posix-spawn -v '0.3.6' Building native extensions. This could take a while... ERROR: Error installing posix-spawn: ERROR: Failed to build gem native extension. /Users/kamil/.rbenv/versions/1.9.3-p0/bin/ruby extconf.rb creating Makefile make compiling posix-spawn.c make: gcc-4.2: No such file or directory mak