diff --git a/Gemfile.lock b/Gemfile.lock
index 384757b4..11f31dbd 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -100,4 +100,4 @@ DEPENDENCIES
   tailwindcss-rails!
 
 BUNDLED WITH
-   2.3.14
+   2.3.25
diff --git a/README.md b/README.md
index db1a12cd..fb1279d4 100644
--- a/README.md
+++ b/README.md
@@ -48,6 +48,10 @@ If you are running `rails tailwindcss:watch` as a process in a Docker container,
 If you are running `rails tailwindcss:watch` on a system that doesn't fully support file system events, pass a `poll` argument to the task to instruct tailwindcss to instead use polling: `rails tailwindcss:watch[poll]`. If you use `bin/dev` then you should modify your `Procfile.dev`.
 
 
+### Using postcss
+
+The tailwind cli supports passing a postcss.config.js file. This might be necessary if you want to use postcss plugins (e.g. postcss-css-variables). This gem checks if a postcss.config.js exists, in which case it is used for building tailwind assets.
+
 ### Debugging with unminified assets
 
 If you want unminified assets, you can pass a `debug` argument to the rake task, i.e. `rails tailwindcss:build[debug]` or `rails tailwindcss:watch[debug]`.
@@ -147,6 +151,14 @@ The inline version also works:
 <section class="bg-[url('image.svg')]">Has the image as it's background</section>
 ```
 
+### Contributing
+
+If you want to fork this repo and test this gem locally in your projects, you will need to run `rake package` (the process this gem uses to generate platform-related gem versions, e.g. x86_64-linux, x86_64-darwin, etc). You can now point the local version of the gem in your Gemfile:
+
+```ruby
+gem 'tailwindcss-rails', '2.0.18', path: '/path/to/your/local/gem'
+```
+
 ## License
 
 Tailwind for Rails is released under the [MIT License](https://opensource.org/licenses/MIT).
diff --git a/lib/tailwindcss/commands.rb b/lib/tailwindcss/commands.rb
index e7f34cb5..e5d703a5 100644
--- a/lib/tailwindcss/commands.rb
+++ b/lib/tailwindcss/commands.rb
@@ -55,7 +55,7 @@ def executable(
         exe_path
       end
 
-      def compile_command(debug: false, **kwargs)
+      def compile_command(debug: false, postcss: false, **kwargs)
         [
           executable(**kwargs),
           "-i", Rails.root.join("app/assets/stylesheets/application.tailwind.css").to_s,
@@ -63,13 +63,15 @@ def compile_command(debug: false, **kwargs)
           "-c", Rails.root.join("config/tailwind.config.js").to_s,
         ].tap do |command|
           command << "--minify" unless debug
+          command << "--postcss" if postcss
         end
       end
 
-      def watch_command(poll: false, **kwargs)
+      def watch_command(poll: false, postcss: false, **kwargs)
         compile_command(**kwargs).tap do |command|
           command << "-w"
           command << "-p" if poll
+          command << "--postcss" if postcss
         end
       end
     end
diff --git a/lib/tasks/build.rake b/lib/tasks/build.rake
index bd407214..e3691670 100644
--- a/lib/tasks/build.rake
+++ b/lib/tasks/build.rake
@@ -2,7 +2,7 @@ namespace :tailwindcss do
   desc "Build your Tailwind CSS"
   task :build do |_, args|
     debug = args.extras.include?("debug")
-    command = Tailwindcss::Commands.compile_command(debug: debug)
+    command = Tailwindcss::Commands.compile_command(debug: debug, postcss: use_postcss?)
     puts command.inspect if args.extras.include?("verbose")
     system(*command, exception: true)
   end
@@ -11,10 +11,14 @@ namespace :tailwindcss do
   task :watch do |_, args|
     debug = args.extras.include?("debug")
     poll = args.extras.include?("poll")
-    command = Tailwindcss::Commands.watch_command(debug: debug, poll: poll)
+    command = Tailwindcss::Commands.watch_command(debug: debug, poll: poll, postcss: use_postcss?)
     puts command.inspect if args.extras.include?("verbose")
     system(*command)
   end
+
+  def use_postcss?
+    File.exist?(Rails.root.join("postcss.config.js"))
+  end
 end
 
 Rake::Task["assets:precompile"].enhance(["tailwindcss:build"])