title: Installing Compass on Mac OS X 10.12 Sierra
body: <p>I am working on two separate machines; one that has Compass installed on it from when the machine was running OS X Yosemite (happy with this one); and one that I am trying to install Compass on that is currently running OS X Sierra (Not so happy about this one).</p>
  
  <p>I had some trouble back in the day with <code>gem install compass</code> while running Yosemite and after searching Stack it seemed that the issue was a user could no longer write to the specified directory they were trying to when running this command. Some suggested using running <code>sudo gem install compass</code> (and this is how I got my first machine running Compass).</p>
  
  <p>With this second machine I run <code>sudo gem install compass</code> and received the following error:</p>
  
  <pre><code>Building native extensions.  This could take a while...
  ERROR:  Error installing compass:
      ERROR: Failed to build gem native extension.
  
      /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb
  mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/include/ruby.h
  
  
  Gem files will remain installed in /Library/Ruby/Gems/2.0.0/gems/ffi-1.9.14 for inspection.
  Results logged to /Library/Ruby/Gems/2.0.0/gems/ffi-1.9.14/ext/ffi_c/gem_make.out
  </code></pre>
  
  <p>I am not very familiar with CLI. Why am I unable to install Compass on Mac OS X Sierra 10.12?</p>