README.md in cssbundling-rails-0.1.2 vs README.md in cssbundling-rails-0.1.4

@@ -13,10 +13,10 @@
 You can configure your bundler options in the `build:css` script in `package.json` or via the installer-generated `tailwind.config.js` for Tailwind or `postcss.config.js` for PostCSS.
 
 
 ## Installation
 
-You must already have node and yarn installed on your system. Then:
+You must already have node and yarn installed on your system. You will also need npx version 7.1.0 or later. Then:
 
 1. Add `cssbundling-rails` to your Gemfile with `gem 'cssbundling-rails'`
 2. Run `./bin/bundle install`
 3. Run `./bin/rails css:install:[tailwind|postcss|sass]`