gen install compass failed

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          ID: compass
    Function: cmd.run
        Name: gem install compass
      Result: False
     Comment: Command "gem install compass" run
     Changes:
              ----------
              pid:
                  12496
              retcode:
                  1
              stderr:
                  ERROR:  Error installing compass:
                  	ERROR: Failed to build gem native extension.

                          /usr/bin/ruby1.9.1 extconf.rb
                  /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load such file -- mkmf (LoadError)
                  	from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
                  	from extconf.rb:4:in `<main>'


                  Gem files will remain installed in /var/lib/gems/1.9.1/gems/ffi-1.9.3 for inspection.
                  Results logged to /var/lib/gems/1.9.1/gems/ffi-1.9.3/ext/ffi_c/gem_make.out
              stdout:
                  Building native extensions.  This could take a while...
----------