diff --git a/index.js b/index.js
index 48cbb60..84822a4 100644
--- a/index.js
+++ b/index.js
@@ -1,6 +1,5 @@
 "use strict"
 
-var defaults = require('defaults')
 var combining = require('./combining')
 
 var DEFAULTS = {
@@ -13,7 +12,7 @@ module.exports = function wcwidth(str) {
 }
 
 module.exports.config = function(opts) {
-  opts = defaults(opts || {}, DEFAULTS)
+  opts = Object.assign({}, DEFAULTS, opts)
   return function wcwidth(str) {
     return wcswidth(str, opts)
   }
diff --git a/package.json b/package.json
index eb2df9d..8c8ab6d 100644
--- a/package.json
+++ b/package.json
@@ -7,8 +7,8 @@
     "Woong Jun <woong.jun@gmail.com> (http://code.woong.org/)"
   ],
   "main": "index.js",
-  "dependencies": {
-    "defaults": "^1.0.3"
+  "engines": {
+    "node": ">=4"
   },
   "devDependencies": {
     "tape": "^4.5.1"