diff --git a/.eslintrc.json b/.eslintrc.json
new file mode 100644
index 0000000..c0dd88b
--- /dev/null
+++ b/.eslintrc.json
@@ -0,0 +1,85 @@
+{
+  "env": {
+    "node": true,
+    "es6": true
+  },
+  "rules": {
+    "block-spacing": [2, "always"],
+    "brace-style": [2, "1tbs", {"allowSingleLine": true}],
+    "comma-style": [2, "last"],
+    "func-style": [2, "expression"],
+    "semi": [2, "always"],
+    "quotes": [2, "single", "avoid-escape"],
+    "indent": [2, 2, {"SwitchCase": 1}],
+    "dot-location": [2, "property"],
+    "camelcase": [1, {"properties": "always"}],
+    "comma-spacing": [2, {"before": false, "after": true}],
+    "comma-dangle": [2, "never"],
+    "semi-spacing": [2, {"before": false, "after": true}],
+    "curly": [2, "multi-line", "consistent"],
+    "no-debugger": 2,
+    "no-dupe-args": 2,
+    "no-dupe-keys": 2,
+    "no-duplicate-case": 2,
+    "no-empty": 2,
+    "no-ex-assign": 2,
+    "no-extra-semi": 2,
+    "no-func-assign": 2,
+    "no-irregular-whitespace": 2,
+    "no-sparse-arrays": 2,
+    "no-unexpected-multiline": 2,
+    "no-unreachable": 2,
+    "no-unused-vars": [2, {"varsIgnorePattern": "ignored"}],
+    "valid-typeof": 2,
+    "eqeqeq": [2, "allow-null"],
+    "no-array-constructor": 2,
+    "no-caller": 2,
+    "no-eval": 2,
+    "no-extend-native": 2,
+    "no-extra-bind": 2,
+    "no-fallthrough": 2,
+    "no-labels": 2,
+    "no-iterator": 2,
+    "no-magic-numbers": [1, {"ignore": [-1, 0, 1, 2, 3, 4, 5, 6, 7, 8]}],
+    "no-multi-spaces": 2,
+    "no-native-reassign": 2,
+    "no-new-func": 2,
+    "no-new-wrappers": 2,
+    "no-new": 2,
+    "no-octal-escape": 2,
+    "no-octal": 2,
+    "no-redeclare": 2,
+    "no-self-compare": 2,
+    "no-sequences": 2,
+    "no-unused-expressions": 2,
+    "no-useless-call": 2,
+    "no-warning-comments": [1, {"terms": ["todo", "fixme", "xxx"], "location": "start"}],
+    "no-with": 2,
+    "new-parens": 2,
+    "wrap-iife": [2, "inside"],
+    "no-catch-shadow": 2,
+    "no-delete-var": 2,
+    "no-shadow-restricted-names": 2,
+    "no-undef": 2,
+    "callback-return": 2,
+    "handle-callback-err": 2,
+    "no-path-concat": 2,
+    "array-bracket-spacing": 2,
+    "eol-last": 2,
+    "no-multiple-empty-lines": [2, {"max": 2}],
+    "no-spaced-func": 2,
+    "no-trailing-spaces": 2,
+    "no-unneeded-ternary": 2,
+    "space-before-keywords": 2,
+    "space-after-keywords": 2,
+    "space-before-blocks": 2,
+    "space-before-function-paren": [2, "never"],
+    "space-in-parens": 2,
+    "space-return-throw-case": 2,
+    "space-unary-ops": [2, {"words": true, "nonwords": false}],
+    "arrow-spacing": [2, {"before": true, "after": true}],
+    "prefer-arrow-callback": 2,
+    "prefer-template": 0,
+    "prefer-const": 2
+  }
+}
diff --git a/index.js b/index.js
index 0fac459..0f0c712 100644
--- a/index.js
+++ b/index.js
@@ -1,35 +1,40 @@
-var CleanCSS = require('clean-css');
-var sysPath = require('path');
-
-function CleanCSSMinifier(config) {
-  if (config == null) config = {};
-  var plugins = config.plugins
-  if (plugins == null) plugins = {};
-  this.options = plugins.cleancss || {};
-}
+'use strict';
 
-CleanCSSMinifier.prototype.brunchPlugin = true;
-CleanCSSMinifier.prototype.type = 'stylesheet';
+const CleanCSS = require('clean-css');
 
-CleanCSSMinifier.prototype.optimize = function(data, path, callback) {
-  var error, optimized;
+class CleanCSSMinifier {
+  constructor(config) {
+    this.options = config && config.plugins && config.plugins.cleancss || {};
+  }
 
-  try {
-    if (this.options.ignored && this.options.ignored.test(path)) {
-      // ignored file path: return non minified
-      return callback(null, data);
+  optimize(params) {
+    const data = params.data;
+    const path = params.path;
+
+    let error, optimized;
+
+    try {
+      if (this.options.ignored && this.options.ignored.test(path)) {
+        // ignored file path: return non minified
+        return Promise.resolve(data);
+      }
+    } catch (e) {
+      return Promise.reject(`error checking ignored files to minify ${e}`);
     }
-  } catch (e) {
-    return callback('error checking ignored files to minify ' + e);
-  }
 
-  try {
-    optimized = new CleanCSS(this.options).minify(data).styles;
-  } catch (_error) {
-    error = "CSS minify failed on " + path + ": " + _error;
-  } finally {
-    callback(error, optimized || data);
+    try {
+      optimized = new CleanCSS(this.options).minify(data).styles;
+    } catch (_error) {
+      error = `CSS minify failed on ${path}: ${_error}`;
+    } finally {
+      if (error) return Promise.reject(error);
+
+      return Promise.resolve(optimized || data);
+    }
   }
-};
+}
+
+CleanCSSMinifier.prototype.brunchPlugin = true;
+CleanCSSMinifier.prototype.type = 'stylesheet';
 
 module.exports = CleanCSSMinifier;
diff --git a/package.json b/package.json
index 2bd92e4..c4df339 100644
--- a/package.json
+++ b/package.json
@@ -10,13 +10,14 @@
     "url": "git@github.com:brunch/clean-css-brunch.git"
   },
   "scripts": {
-    "test": "mocha"
+    "test": "node_modules/.bin/eslint index.js && node_modules/.bin/mocha"
   },
   "dependencies": {
     "clean-css": "^3.4.8"
   },
   "devDependencies": {
     "chai": "^3.4.1",
-    "mocha": "^2.3.4"
+    "mocha": "^2.3.4",
+    "eslint": "^1.10.3"
   }
 }
diff --git a/test.js b/test.js
index 93c43ce..3f82e4e 100644
--- a/test.js
+++ b/test.js
@@ -19,11 +19,10 @@ describe('Plugin', function() {
     var content = '#first { font-size: 14px; color: #b0b; }';
     var expected = '#first{font-size:14px;color:#b0b}';
 
-    plugin.optimize(content, '', function(error, data) {
-      expect(error).not.to.be.ok;
+    plugin.optimize({data: content, path: ''}).then(data => {
       expect(data).to.equal(expected);
       done();
-    });
+    }, error => expect(error).not.to.be.ok);
   });
 
   it('should compile and produce a result clean-css options are reflected in', function(done) {
@@ -37,11 +36,10 @@ describe('Plugin', function() {
     var content = '/*! comment */\n#first { color: red; }\r\n#second { color: blue; }';
     var expected = '#first{color:red}' + eol + '#second{color:#00f}';
 
-    plugin.optimize(content, '', function(error, data) {
-      expect(error).not.to.be.ok;
+    plugin.optimize({data: content, path: ''}).then(data => {
       expect(data).to.equal(expected);
       done();
-    });
+    }, error => expect(error).not.to.be.ok);
   });
 
   it('should return a non minified css if path is in "ignore" list', function(done) {
@@ -52,11 +50,10 @@ describe('Plugin', function() {
     var content = '#first { font-size: 14px; color: #b0b; }';
     var expected = content;
 
-    plugin.optimize(content, 'dist\/ignore-me.css', function(error, data) {
-      expect(error).not.to.be.ok;
+    plugin.optimize({data: content, path: "dist/ignore-me.css"}).then(data => {
       expect(data).to.equal(expected);
       done();
-    });
+    }, error => expect(error).not.to.be.ok);
   });