diff --git a/.travis.yml b/.travis.yml
index 17f302b..dc08449 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,9 +1,8 @@
 language: node_js
 node_js:
-  - "0.10"
-  - "0.12"
   - "4"
   - "6"
+  - "7"
 os:
   - linux
   - osx
diff --git a/README.md b/README.md
index cde67b7..a0bf5d1 100644
--- a/README.md
+++ b/README.md
@@ -32,16 +32,16 @@ Oh, and `limax` is the Latin word for slug.
 ## Usage
 
 ```javascript
-var slug = require('limax');
+import slug from 'limax';
 ```
 
 ### slug(text)
 
 ```javascript
-var latin = slug('i ♥ latin'); // i-love-latin
-var cyrillic = slug('Я люблю русский'); // ya-lyublyu-russkij
-var pinyin = slug('我爱官话'); // wo3-ai4-guan1-hua4
-var romaji = slug('私は ひらがな が大好き'); // ha-hiragana-gaki
+const latin = slug('i ♥ latin'); // i-love-latin
+const cyrillic = slug('Я люблю русский'); // ya-lyublyu-russkij
+const pinyin = slug('我爱官话'); // wo3-ai4-guan1-hua4
+const romaji = slug('私は ひらがな が大好き'); // ha-hiragana-gaki
 ```
 
 ### slug(text, options)
@@ -58,22 +58,22 @@ options:
   * Array, add chars to allowed charMap
 
 ```javascript
-var strich = slug('Ich ♥ Deutsch', {lang: 'de'}); // ich-liebe-deutsch
-var unterstreichen1 = slug('Ich ♥ Deutsch', {lang: 'de', replacement: '_'}); // i_liebe_deutsch
-var unterstreichen2 = slug('Ich ♥ Deutsch', {lang: 'de', separator: '_'}); // i_liebe_deutsch
-var wuYin = slug('弄堂里的菜品赤醬', {tone: false}); // nong-tang-li-di-cai-pin-chi-jiang
+const strich = slug('Ich ♥ Deutsch', {lang: 'de'}); // ich-liebe-deutsch
+const unterstreichen1 = slug('Ich ♥ Deutsch', {lang: 'de', replacement: '_'}); // i_liebe_deutsch
+const unterstreichen2 = slug('Ich ♥ Deutsch', {lang: 'de', separator: '_'}); // i_liebe_deutsch
+const wuYin = slug('弄堂里的菜品赤醬', {tone: false}); // nong-tang-li-di-cai-pin-chi-jiang
 
 // separateNumbers example
-var numbersInWord = slug('hello2world', {separateNumbers: false}); // hello2world 
-var numbersSeparated = slug('hello2world'); // hello-2-world 
+const numbersInWord = slug('hello2world', {separateNumbers: false}); // hello2world
+const numbersSeparated = slug('hello2world'); // hello-2-world
 
 // maintainCase example
-var caseNotMaintained = slug('Hello2World'); // hello-2-world
-var caseMaintained = slug('Hello2World', { maintainCase: true }); // Hello-2-World
+const caseNotMaintained = slug('Hello2World'); // hello-2-world
+const caseMaintained = slug('Hello2World', { maintainCase: true }); // Hello-2-World
 
 // custom example
-var custom1 = slug('hello.world', { custom: ['.'] }); // hello.world
-var custom2 = slug('hello-*-world', { custom: { '*': 'asterisk' } }); // hello-asterisk-world
+const custom1 = slug('hello.world', { custom: ['.'] }); // hello.world
+const custom2 = slug('hello-*-world', { custom: { '*': 'asterisk' } }); // hello-asterisk-world
 ```
 
 ### slug(text, replacement)
@@ -81,7 +81,7 @@ var custom2 = slug('hello-*-world', { custom: { '*': 'asterisk' } }); // hello-a
 Provided to support backwards-compatibility with the `slug` module.
 
 ```javascript
-var underscore = slug('i ♥ unicode', '_'); // i_love_unicode
+const underscore = slug('i ♥ unicode', '_'); // i_love_unicode
 ```
 
 ## Test [![Build Status](https://travis-ci.org/lovell/limax.png?branch=master)](https://travis-ci.org/lovell/limax)
diff --git a/appveyor.yml b/appveyor.yml
index 254df4f..b0b7e18 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -4,10 +4,6 @@ build: off
 platform: x64
 environment:
   matrix:
-  - nodejs_version: "0.12"
-    nodejs_arch: "x86"
-  - nodejs_version: "0.12"
-    nodejs_arch: "x64"
   - nodejs_version: "4"
     nodejs_arch: "x86"
   - nodejs_version: "4"
@@ -16,6 +12,10 @@ environment:
     nodejs_arch: "x86"
   - nodejs_version: "6"
     nodejs_arch: "x64"
+  - nodejs_version: "7"
+    nodejs_arch: "x86"
+  - nodejs_version: "7"
+    nodejs_arch: "x64"
 install:
   - ps: Install-Product node $env:nodejs_version $env:nodejs_arch
   - npm install
diff --git a/lib/limax.js b/lib/limax.js
index 0ccb323..b373d93 100644
--- a/lib/limax.js
+++ b/lib/limax.js
@@ -1,34 +1,27 @@
 'use strict';
 
-var speakingurl = require('speakingurl');
-var pinyin = require('pinyin');
-var hepburn = require('hepburn');
+const speakingurl = require('speakingurl');
+const pinyin = require('pinyin');
+const hepburn = require('hepburn');
 
 module.exports = function(text, opt) {
-  var options = opt || {};
-  var separateNumbers = true;
-
-  if (typeof options === 'string') {
-    options = {separator: options};
-  }
-
-  if (typeof options.separateNumbers !== 'undefined') {
-    separateNumbers = options.separateNumbers;
-  }
+  const options = typeof opt === 'string'
+    ? { separator: opt }
+    : opt || {};
 
   // Remove apostrophes contained within a word
   text = text.replace(/(\S)['\u2018\u2019\u201A\u201B\u2032\u2035\u0301](\S)/g, '$1$2');
 
   // Break out any numbers contained within a word
-  if (separateNumbers) {
+  if (options.separateNumbers !== false) {
     text = text.replace(/([^\d\s])([0-9]+)([^\d\s])/g, '$1 $2 $3');
   }
 
   // Should we remove the separator before a digit where previous word does not end in a digit?
-  var mergeDigitSuffixes = false;
+  let mergeDigitSuffixes = false;
 
   // Language-specific behaviour
-  var lang = options.lang;
+  const lang = options.lang;
   if (typeof lang === 'undefined') {
     if (hepburn.containsKana(text)) {
       // Convert from Japanese Kana using Hepburn romanisation
@@ -39,7 +32,7 @@ module.exports = function(text, opt) {
       // Convert Mandarin Chinese to Pinyin with numeric tones
       mergeDigitSuffixes = true;
       // Should we use tone numbers? (default is true)
-      var tone = (typeof options.tone === 'boolean') ? options.tone : true;
+      const tone = (typeof options.tone === 'boolean') ? options.tone : true;
       text = pinyin(text, {
         'style': tone ? pinyin.STYLE_TONE2 : pinyin.STYLE_NORMAL
       }).join(' ');
@@ -50,19 +43,15 @@ module.exports = function(text, opt) {
     }
   }
   // Convert to slug using speakingurl
-  var separator = options.replacement || options.separator;
-  if (typeof separator !== 'string') {
-    separator = '-';
-  }
-  var slug = speakingurl(text, {
+  const separator = options.replacement || options.separator;
+  const slug = speakingurl(text, {
     lang: lang || 'en',
-    separator: separator,
+    separator: typeof separator === 'string' ? separator : '-',
     maintainCase: options.maintainCase || false,
     custom: options.custom || {}
   });
   // Remove separator before a digit where previous word does not end in a digit
-  if (mergeDigitSuffixes) {
-    slug = slug.replace(/([^0-9])-([0-9])/g, '$1$2');
-  }
-  return slug;
+  return mergeDigitSuffixes
+    ? slug.replace(/([^0-9])-([0-9])/g, '$1$2')
+    : slug;
 };
diff --git a/package.json b/package.json
index 53e494b..04506df 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "limax",
-  "version": "1.4.1",
+  "version": "1.5.0",
   "main": "./lib/limax",
   "description": "Node.js module to generate URL slugs. Another one? This one cares about i18n and transliterates non-Latin scripts to conform to the RFC3986 standard. Mostly API-compatible with similar modules.",
   "repository": {
@@ -8,7 +8,7 @@
     "url": "git://github.com/lovell/limax"
   },
   "engines": {
-    "node": ">=0.10"
+    "node": ">=4"
   },
   "scripts": {
     "test": "node test/unit"
@@ -39,7 +39,7 @@
   "license": "Apache-2.0",
   "dependencies": {
     "hepburn": "^1.0.0",
-    "pinyin": "2.6.2",
-    "speakingurl": "^10.0.0"
+    "pinyin": "^2.8.2",
+    "speakingurl": "^13.0.0"
   }
 }
diff --git a/test/unit.js b/test/unit.js
index 7134d03..e60a10a 100644
--- a/test/unit.js
+++ b/test/unit.js
@@ -1,9 +1,9 @@
 'use strict';
 
-var assert = require('assert');
-var slug = require('../lib/limax');
+const assert = require('assert');
+const slug = require('../lib/limax');
 
-var tests = {
+const tests = {
   'i ♥ latin': 'i-love-latin',
   'Я люблю русский': 'ya-lyublyu-russkii',
   '私は ひらがな が大好き': 'ha-hiragana-gaki',
@@ -13,7 +13,7 @@ var tests = {
   'The User\'s Guide': 'the-users-guide',
   'The User’s Guide': 'the-users-guide',
   // https://github.com/lovell/limax/issues/4
-  '弄堂里的菜品赤醬': 'nong4-tang2-li3-di2-cai4-pin3-chi4-jiang4',
+  '弄堂里的菜品赤醬': 'nong4-tang2-li3-de-cai4-pin3-chi4-jiang4',
   // https://github.com/lovell/limax/issues/12
   '12345': '12345',
   'one 2three': 'one-2three',
@@ -22,34 +22,34 @@ var tests = {
 };
 
 Object.keys(tests).forEach(function(test) {
-  var actual = slug(test);
-  var expected = tests[test];
+  const actual = slug(test);
+  const expected = tests[test];
   assert.strictEqual(actual, expected);
 });
 
 Object.keys(tests).forEach(function(test) {
-  var actual = slug(test, '_');
-  var expected = tests[test].replace(/-/g, '_');
+  const actual = slug(test, '_');
+  const expected = tests[test].replace(/-/g, '_');
   assert.strictEqual(actual, expected);
 });
 
 Object.keys(tests).forEach(function(test) {
-  var actual = slug(test, {replacement: '_'});
-  var expected = tests[test].replace(/-/g, '_');
+  const actual = slug(test, {replacement: '_'});
+  const expected = tests[test].replace(/-/g, '_');
   assert.strictEqual(actual, expected);
 });
 
 Object.keys(tests).forEach(function(test) {
-  var actual = slug(test, {separator: '_'});
-  var expected = tests[test].replace(/-/g, '_');
+  const actual = slug(test, {separator: '_'});
+  const expected = tests[test].replace(/-/g, '_');
   assert.strictEqual(actual, expected);
 });
 
 assert.strictEqual(slug('Ich ♥ Deutsch', {lang: 'de'}), 'ich-liebe-deutsch');
 
 // https://github.com/lovell/limax/issues/4
-assert.strictEqual(slug('弄堂里的菜品赤醬', {tone: true}), 'nong4-tang2-li3-di2-cai4-pin3-chi4-jiang4');
-assert.strictEqual(slug('弄堂里的菜品赤醬', {tone: false}), 'nong-tang-li-di-cai-pin-chi-jiang');
+assert.strictEqual(slug('弄堂里的菜品赤醬', {tone: true}), 'nong4-tang2-li3-de-cai4-pin3-chi4-jiang4');
+assert.strictEqual(slug('弄堂里的菜品赤醬', {tone: false}), 'nong-tang-li-de-cai-pin-chi-jiang');
 
 // https://github.com/lovell/limax/issues/14
 assert.strictEqual(slug('hello2world', { separateNumbers: false }), 'hello2world');