diff --git a/index.js b/index.js
index 403e3f2..8501913 100644
--- a/index.js
+++ b/index.js
@@ -1,19 +1,17 @@
 'use strict';
-var hasGulplog = require('has-gulplog');
-var micromatch = require('micromatch');
-var unique = require('array-unique');
-var findup = require('findup-sync');
-var resolve = require('resolve');
-var path = require('path');
+const hasGulplog = require('has-gulplog');
+const micromatch = require('micromatch');
+const unique = require('array-unique');
+const findup = require('findup-sync');
+const resolve = require('resolve');
+const path = require('path');
 
 function arrayify(el) {
   return Array.isArray(el) ? el : [el];
 }
 
 function camelize(str) {
-  return str.replace(/-(\w)/g, function(m, p1) {
-    return p1.toUpperCase();
-  });
+  return str.replace(/-(\w)/g, (m, p1) => p1.toUpperCase());
 }
 
 // code from https://github.com/gulpjs/gulp-util/blob/master/lib/log.js
@@ -22,18 +20,18 @@ function camelize(str) {
 function logger() {
   if (hasGulplog()) {
     // specifically deferring loading here to keep from registering it globally
-    var gulplog = require('gulplog');
+    const gulplog = require('gulplog');
     gulplog.info.apply(gulplog, arguments);
   } else {
     // specifically defering loading because it might not be used
-    var fancylog = require('fancy-log');
+    const fancylog = require('fancy-log');
     fancylog.apply(null, arguments);
   }
 }
 
 function getPattern(options) {
-  var defaultPatterns = ['gulp-*', 'gulp.*', '@*/gulp{-,.}*'];
-  var overridePattern = 'overridePattern' in options ? !!options.overridePattern : true;
+  const defaultPatterns = ['gulp-*', 'gulp.*', '@*/gulp{-,.}*'];
+  const overridePattern = 'overridePattern' in options ? !!options.overridePattern : true;
   if (overridePattern) {
     return arrayify(options.pattern || defaultPatterns);
   }
@@ -41,29 +39,29 @@ function getPattern(options) {
 }
 
 module.exports = function(options) {
-  var finalObject = {};
-  var configObject;
-  var requireFn;
+  const finalObject = {};
+  let configObject;
+  let requireFn;
   options = options || {};
 
-  var DEBUG = options.DEBUG || false;
-  var pattern = getPattern(options);
-  var config = options.config || findup('package.json', { cwd: parentDir });
-  var scope = arrayify(options.scope || ['dependencies', 'devDependencies', 'peerDependencies']);
-  var replaceString = options.replaceString || /^gulp(-|\.)/;
-  var camelizePluginName = options.camelize !== false;
-  var lazy = 'lazy' in options ? !!options.lazy : true;
-  var renameObj = options.rename || {};
-  var maintainScope = 'maintainScope' in options ? !!options.maintainScope : true;
+  const DEBUG = options.DEBUG || false;
+  const pattern = getPattern(options);
+  const config = options.config || findup('package.json', { cwd: parentDir });
+  const scope = arrayify(options.scope || ['dependencies', 'devDependencies', 'peerDependencies']);
+  const replaceString = options.replaceString || /^gulp(-|\.)/;
+  const camelizePluginName = options.camelize !== false;
+  const lazy = 'lazy' in options ? !!options.lazy : true;
+  const renameObj = options.rename || {};
+  const maintainScope = 'maintainScope' in options ? !!options.maintainScope : true;
 
-  logDebug('Debug enabled with options: ' + JSON.stringify(options));
+  logDebug(`Debug enabled with options: ${JSON.stringify(options)}`);
 
-  var renameFn = options.renameFn || function(name) {
+  const renameFn = options.renameFn || function(name) {
     name = name.replace(replaceString, '');
     return camelizePluginName ? camelize(name) : name;
   };
 
-  var postRequireTransforms = options.postRequireTransforms || {};
+  const postRequireTransforms = options.postRequireTransforms || {};
 
   if (typeof options.requireFn === 'function') {
     requireFn = options.requireFn;
@@ -71,7 +69,7 @@ module.exports = function(options) {
     requireFn = function(name) {
       // This searches up from the specified package.json file, making sure
       // the config option behaves as expected. See issue #56.
-      var src = resolve.sync(name, { basedir: path.dirname(config) });
+      const src = resolve.sync(name, { basedir: path.dirname(config) });
       return require(src);
     };
   } else {
@@ -84,47 +82,45 @@ module.exports = function(options) {
     throw new Error('Could not find dependencies. Do you have a package.json file in your project?');
   }
 
-  var names = scope.reduce(function(result, prop) {
-    return result.concat(Object.keys(configObject[prop] || {}));
-  }, []);
+  const names = scope.reduce((result, prop) => result.concat(Object.keys(configObject[prop] || {})), []);
 
-  logDebug(names.length + ' plugin(s) found: ' + names.join(' '));
+  logDebug(`${names.length} plugin(s) found: ${names.join(' ')}`);
 
   pattern.push('!gulp-load-plugins');
 
   function logDebug(message) {
     if (DEBUG) {
-      logger('gulp-load-plugins: ' + message);
+      logger(`gulp-load-plugins: ${message}`);
     }
   }
 
   function defineProperty(object, transform, requireName, name, maintainScope) {
-    var err;
+    let err;
     if (object[requireName]) {
-      logDebug('error: defineProperty ' + name);
+      logDebug(`error: defineProperty ${name}`);
       err = maintainScope
-        ? 'Could not define the property "' + requireName + '", you may have repeated dependencies in your package.json like' + ' "gulp-' + requireName + '" and ' + '"' + requireName + '"'
-        : 'Could not define the property "' + requireName + '", you may have repeated a dependency in another scope like' + ' "gulp-' + requireName + '" and ' + '"@foo/gulp-' + requireName + '"';
+        ? `Could not define the property "${requireName}", you may have repeated dependencies in your package.json like` + ` "gulp-${requireName}" and ` + `"${requireName}"`
+        : `Could not define the property "${requireName}", you may have repeated a dependency in another scope like` + ` "gulp-${requireName}" and ` + `"@foo/gulp-${requireName}"`;
       throw new Error(err);
     }
 
     if (lazy) {
-      logDebug('lazyload: adding property ' + requireName);
+      logDebug(`lazyload: adding property ${requireName}`);
       Object.defineProperty(object, requireName, {
         enumerable: true,
         get: function() {
-          logDebug('lazyload: requiring ' + name + '...');
+          logDebug(`lazyload: requiring ${name}...`);
           return transform(requireName, requireFn(name));
         }
       });
     } else {
-      logDebug('requiring ' + name + '...');
+      logDebug(`requiring ${name}...`);
       object[requireName] = transform(requireName, requireFn(name));
     }
   }
 
   function getRequireName(name) {
-    var requireName;
+    let requireName;
 
     if (renameObj[name]) {
       requireName = options.rename[name];
@@ -132,28 +128,28 @@ module.exports = function(options) {
       requireName = renameFn(name);
     }
 
-    logDebug('renaming ' + name + ' to ' + requireName);
+    logDebug(`renaming ${name} to ${requireName}`);
 
     return requireName;
   }
 
   function applyTransform(requireName, plugin) {
-    var transform = postRequireTransforms[requireName];
+    const transform = postRequireTransforms[requireName];
 
     if (transform && typeof transform === 'function') { // if postRequireTransform function is passed, pass it the plugin and return it
-      logDebug('transforming ' + requireName);
+      logDebug(`transforming ${requireName}`);
       return transform(plugin);
     } else {
       return plugin; // if no postRequireTransform function passed, return the plugin as is
     }
   }
 
-  var scopeTest = new RegExp('^@');
-  var scopeDecomposition = new RegExp('^@(.+)/(.+)');
+  const scopeTest = new RegExp('^@');
+  const scopeDecomposition = new RegExp('^@(.+)/(.+)');
 
-  unique(micromatch(names, pattern)).forEach(function(name) {
-    var decomposition;
-    var fObject = finalObject;
+  unique(micromatch(names, pattern)).forEach((name) => {
+    let decomposition;
+    let fObject = finalObject;
     if (scopeTest.test(name)) {
       decomposition = scopeDecomposition.exec(name);
       if (maintainScope) {
@@ -172,7 +168,7 @@ module.exports = function(options) {
   return finalObject;
 };
 
-var parentDir = path.dirname(module.parent.filename);
+const parentDir = path.dirname(module.parent.filename);
 
 // Necessary to get the current `module.parent` and resolve paths correctly.
 delete require.cache[__filename];
diff --git a/package.json b/package.json
index 39fa5cb..5753ec5 100644
--- a/package.json
+++ b/package.json
@@ -10,6 +10,9 @@
   "files": [
     "index.js"
   ],
+  "engines": {
+		"node": ">=4"
+  },
   "repository": "jackfranklin/gulp-load-plugins",
   "keywords": [
     "gulpfriendly",
diff --git a/test/index.js b/test/index.js
index ac43008..ecc4d26 100644
--- a/test/index.js
+++ b/test/index.js
@@ -1,17 +1,17 @@
 'use strict';
-var assert = require('assert');
-var sinon = require('sinon');
-var capture = require('capture-stream');
-var path = require('path');
+const assert = require('assert');
+const sinon = require('sinon');
+const capture = require('capture-stream');
+const path = require('path');
 
-var gulpLoadPlugins = (function() {
-  var wrapInFunc = function(value) {
+const gulpLoadPlugins = (function() {
+  const wrapInFunc = function(value) {
     return function() {
       return value;
     };
   };
 
-  var proxyquire = require('proxyquire').noCallThru();
+  const proxyquire = require('proxyquire').noCallThru();
 
   return proxyquire('../', {
     'gulp-foo': wrapInFunc({ name: 'foo' }),
@@ -71,9 +71,9 @@ describe('configuration', function() {
 });
 
 // Contains common tests with and without lazy mode.
-var commonTests = function(lazy) {
+const commonTests = function(lazy) {
   it('loads things in', function() {
-    var x = gulpLoadPlugins({
+    const x = gulpLoadPlugins({
       lazy: lazy,
       config: {
         dependencies: {
@@ -103,7 +103,7 @@ var commonTests = function(lazy) {
   });
 
   it('can take a pattern override', function() {
-    var x = gulpLoadPlugins({
+    const x = gulpLoadPlugins({
       lazy: lazy,
       pattern: 'jack-*',
       replaceString: 'jack-',
@@ -122,7 +122,7 @@ var commonTests = function(lazy) {
   });
 
   it('can extend the patterns', function() {
-    var x = gulpLoadPlugins({
+    const x = gulpLoadPlugins({
       lazy: lazy,
       config: {
         dependencies: {
@@ -141,7 +141,7 @@ var commonTests = function(lazy) {
   });
 
   it('allows camelizing to be turned off', function() {
-    var x = gulpLoadPlugins({
+    const x = gulpLoadPlugins({
       lazy: lazy,
       camelize: false,
       config: {
@@ -157,7 +157,7 @@ var commonTests = function(lazy) {
   });
 
   it('camelizes plugins name by default', function() {
-    var x = gulpLoadPlugins({
+    const x = gulpLoadPlugins({
       lazy: lazy,
       config: {
         dependencies: {
@@ -172,7 +172,7 @@ var commonTests = function(lazy) {
   });
 
   it('lets something be completely renamed', function() {
-    var x = gulpLoadPlugins({
+    const x = gulpLoadPlugins({
       lazy: lazy,
       config: { dependencies: { 'gulp-foo': '1.0.0' } },
       rename: { 'gulp-foo': 'bar' }
@@ -182,9 +182,9 @@ var commonTests = function(lazy) {
   });
 
   it('outputs debug statements', function() {
-    var restore = capture(process.stdout);
+    const restore = capture(process.stdout);
     try {
-      var x = gulpLoadPlugins({
+      const x = gulpLoadPlugins({
         lazy: lazy,
         DEBUG: true,
         config: { dependencies: { 'gulp-foo': '*' } }
@@ -198,12 +198,12 @@ var commonTests = function(lazy) {
       throw err;
     }
 
-    var output = restore('true');
+    const output = restore('true');
     assert(output.indexOf('gulp-load-plugins') !== -1, 'Expected output to be logged to stdout');
   });
 
   it('supports loading scopped package as a nested reference', function() {
-    var x = gulpLoadPlugins({
+    const x = gulpLoadPlugins({
       lazy: lazy,
       config: { dependencies: { '@myco/gulp-test-plugin': '1.0.0' } }
     });
@@ -212,7 +212,7 @@ var commonTests = function(lazy) {
   });
 
   it('supports loading scopped package as a top-level reference', function() {
-    var x = gulpLoadPlugins({
+    const x = gulpLoadPlugins({
       lazy: lazy,
       maintainScope: false,
       config: { dependencies: { '@myco/gulp-test-plugin': '1.0.0' } }
@@ -222,7 +222,7 @@ var commonTests = function(lazy) {
   });
 
   it('supports custom rename functions', function () {
-    var x = gulpLoadPlugins({
+    const x = gulpLoadPlugins({
       renameFn: function () {
         return 'baz';
       },
@@ -243,7 +243,7 @@ var commonTests = function(lazy) {
   });
 
   it('supports transforming', function() {
-    var x = gulpLoadPlugins({
+    const x = gulpLoadPlugins({
       lazy: lazy,
       config: { dependencies: { 'gulp-foo': '1.0.0' } },
       postRequireTransforms: {
@@ -261,7 +261,7 @@ var commonTests = function(lazy) {
 describe('no lazy loading', function() {
   commonTests(false);
 
-  var spy;
+  let spy;
   before(function() {
     spy = sinon.spy();
     gulpLoadPlugins({
@@ -286,7 +286,7 @@ describe('no lazy loading', function() {
 describe('with lazy loading', function() {
   commonTests(true);
 
-  var x, spy;
+  let x, spy;
   before(function() {
     spy = sinon.spy();
     x = gulpLoadPlugins({
@@ -315,7 +315,7 @@ describe('with lazy loading', function() {
 
 describe('common functionality', function () {
   it('throws a sensible error when not found', function () {
-    var x = gulpLoadPlugins({ config: path.join(__dirname, '/package.json') });
+    const x = gulpLoadPlugins({ config: path.join(__dirname, '/package.json') });
 
     assert.throws(function () {
       x.oops();
@@ -323,7 +323,7 @@ describe('common functionality', function () {
   });
 
   it('allows you to use in a lower directory', function() {
-    var plugins = require('../')();
+    const plugins = require('../')();
     assert.ok(typeof plugins.test === 'function');
   });
 });