Fail to install nokogiri 1.8.1 in macOS High Sierra

An error occurred while installing nokogiri (1.8.1), and Bundler cannot continue.
Make sure that `gem install nokogiri -v '1.8.1'` succeeds before bundling.

In Gemfile:
  activeadmin_settings_cached was resolved to 2.0.1, which depends on
    rails-settings-cached was resolved to 0.5.6, which depends on
      rails was resolved to 5.0.6, which depends on
        actioncable was resolved to 5.0.6, which depends on
          actionpack was resolved to 5.0.6, which depends on
            actionview was resolved to 5.0.6, which depends on
              rails-dom-testing was resolved to 2.0.3, which depends on
                nokogiri
➜  parker-quote git:(master) gem install nokogiri -v '1.8.1' -- --use-system-libraries=true --with-xml2-include="$(xcrun --show-sdk-path)"/usr/include/libxml2
Building native extensions with: '--use-system-libraries=true --with-xml2-include=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/usr/include/libxml2'
This could take a while...
Successfully installed nokogiri-1.8.1
Parsing documentation for nokogiri-1.8.1
Installing ri documentation for nokogiri-1.8.1
Done installing documentation for nokogiri after 12 seconds
1 gem installed

👍

When using bundler:

bundle config build.nokogiri "--use-system-libraries=true --with-xml2-include=$(xcrun --show-sdk-path)/usr/include/libxml2"