diff --git a/README.md b/README.md
index 8929958..e2d6a1b 100644
--- a/README.md
+++ b/README.md
@@ -36,14 +36,6 @@ npm install postcss-color-functional-notation --save-dev
 
 Use [PostCSS Color Functional Notation] to process your CSS:
 
-```js
-const postcssColorFunctionalNotation = require('postcss-color-functional-notation');
-
-postcssColorFunctionalNotation.process(YOUR_CSS /*, processOptions, pluginOptions */);
-```
-
-Or use it as a [PostCSS] plugin:
-
 ```js
 const postcss = require('postcss');
 const postcssColorFunctionalNotation = require('postcss-color-functional-notation');
diff --git a/package.json b/package.json
index 49fcdca..8bf6c21 100644
--- a/package.json
+++ b/package.json
@@ -26,15 +26,18 @@
     "node": ">=10.0.0"
   },
   "dependencies": {
-    "postcss": "^7.0.27",
-    "postcss-values-parser": "^3.2.0"
+    "postcss-values-parser": "^5.0.0"
+  },
+  "peerDependencies": {
+    "postcss": "^8.0.0"
   },
   "devDependencies": {
     "@babel/core": "^7.9.0",
     "@babel/preset-env": "^7.9.5",
     "babel-eslint": "^10.1.0",
     "eslint": "^6.8.0",
-    "postcss-tape": "^5.0.2",
+    "postcss": "^8.0.5",
+    "postcss-tape": "^6.0.0",
     "pre-commit": "^1.2.2",
     "rollup": "^2.7.2",
     "rollup-plugin-babel": "^4.4.0"
diff --git a/src/index.js b/src/index.js
index 4e2200c..202e0b0 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,18 +1,18 @@
-import postcss from 'postcss'
 import onCSSDeclaration from './onCSSDeclaration'
 import options from './options'
 
 /** Transform space and slash separated color functions in CSS. */
-const postcssPlugin = postcss.plugin('postcss-color-functional-notation', opts => {
+export default function postcssColorFunctionalNotation(opts) {
 	options.preserve = 'preserve' in Object(opts) ? Boolean(opts.preserve) : false
 
-	return root => {
-		root.walkDecls(onCSSDeclaration)
+	return {
+		postcssPlugin: 'postcss-color-functional-notation',
+		Declaration: onCSSDeclaration
 	}
-})
+}
 
-export default postcssPlugin
+postcssColorFunctionalNotation.postcss = true
 
-/** @typedef {import('postcss').Root} CSSRoot */ 
-/** @typedef {(root: CSSRoot) => void} PostCSSTransformCallback */ 
-/** @typedef {(opts: options) => PostCSSTransformCallback} PostCSSPluginInitializer */ 
+/** @typedef {import('postcss').Root} CSSRoot */
+/** @typedef {(root: CSSRoot) => void} PostCSSTransformCallback */
+/** @typedef {(opts: options) => PostCSSTransformCallback} PostCSSPluginInitializer */
diff --git a/src/onCSSFunction.js b/src/onCSSFunction.js
index e4781fb..2bf9e19 100644
--- a/src/onCSSFunction.js
+++ b/src/onCSSFunction.js
@@ -10,10 +10,6 @@ const onCSSFunction = node => {
 		const isRgbWithNumbers = isRgbColorFunctionName(name) && isRgbNumberFunctionContents(nodes)
 		const isRgbWithPercents = isRgbColorFunctionName(name) && isRgbPercentFunctionContents(nodes)
 
-		if (name === 'hsl' && !isHsl) {
-			console.log([name, isHue(nodes[0])], nodes[0])
-		}
-
 		if (isHsl || isRgbWithNumbers || isRgbWithPercents) {
 			// rename the Color function to `hsl` or `rgb`
 			Object.assign(node, { name: isHsl ? 'hsl' : 'rgb' })