diff --git a/package.json b/package.json
index 77b80f6..9ad98d2 100644
--- a/package.json
+++ b/package.json
@@ -13,24 +13,22 @@
   "bugs": "https://github.com/goto-bus-stop/plug-login/issues",
   "author": "René Kooi <rene@kooi.me>",
   "engines": {
-    "node": ">= 0.12"
+    "node": ">= 4"
   },
   "dependencies": {
     "cookie": "^0.3.1",
     "got": "^6.5.0",
+    "object-assign": "^4.1.0",
     "promise-props": "^1.0.0"
   },
   "devDependencies": {
-    "babel-cli": "^6.7.7",
-    "babel-plugin-transform-object-rest-spread": "^6.5.0",
-    "babel-preset-es2015": "^6.18.0",
-    "babel-register": "^6.5.0",
+    "buble": "^0.14.2",
     "mocha": "^3.0.2",
     "standard": "^8.0.0"
   },
   "scripts": {
-    "prepublish": "npm run babel",
-    "babel": "babel --out-dir lib src",
-    "test": "mocha --compilers js:babel-register && standard"
+    "prepublish": "npm run build",
+    "build": "buble --output lib --target node:4 --objectAssign assign src",
+    "test": "npm run build && mocha && standard"
   }
 }
diff --git a/src/index.js b/src/index.js
index 3ffe9ff..3cfe93a 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,6 +1,8 @@
-import got from 'got'
-import { parse, serialize } from 'cookie'
-import props from 'promise-props'
+'use strict'
+const got = require('got')
+const { parse, serialize } = require('cookie')
+const props = require('promise-props')
+const assign = require('object-assign')
 
 const DEFAULT_HOST = 'https://plug.dj'
 
@@ -41,7 +43,7 @@ function makeSessionCookieHeader (session) {
 
 function addCookieToHeaders (opts, session) {
   if (!opts.headers || !opts.headers.cookie) {
-    opts.headers = Object.assign(opts.headers || {}, {
+    opts.headers = assign(opts.headers || {}, {
       cookie: makeSessionCookieHeader(session)
     })
   }
diff --git a/test/test.js b/test/test.js
index f279050..3bd8f90 100644
--- a/test/test.js
+++ b/test/test.js
@@ -1,7 +1,9 @@
 /* global describe, it, before */
-import got from 'got'
-import { strictEqual as eq, fail, ok } from 'assert'
-import login from '../src'
+'use strict'
+
+const got = require('got')
+const assert = require('assert')
+const login = require('../lib')
 
 const host = process.env.PLUG_LOGIN_HOST || 'https://plug.dj'
 
@@ -17,8 +19,8 @@ describe('plug-login', function () {
     })
   )
 
-  ok(process.env.PLUG_LOGIN_NAME, 'pass your test email in the PLUG_LOGIN_NAME env var')
-  ok(process.env.PLUG_LOGIN_PASS, 'pass your test password in the PLUG_LOGIN_PASS env var')
+  assert.ok(process.env.PLUG_LOGIN_NAME, 'pass your test email in the PLUG_LOGIN_NAME env var')
+  assert.ok(process.env.PLUG_LOGIN_PASS, 'pass your test password in the PLUG_LOGIN_PASS env var')
 
   const args = {
     email: process.env.PLUG_LOGIN_NAME,
@@ -28,39 +30,39 @@ describe('plug-login', function () {
   const INVALID_EMAIL = 'invalid-email@invalid-domain.com'
   const INVALID_PASSWORD = 'not_the_password'
   it('cannot login with invalid credentials', () =>
-    login(INVALID_EMAIL, INVALID_PASSWORD, { host }).then(fail, (result) => {
-      ok(result)
+    login(INVALID_EMAIL, INVALID_PASSWORD, { host }).then(assert.fail, (result) => {
+      assert.ok(result)
     })
   )
 
   it('can login with valid credentials', () =>
     login(args.email, args.password, { host }).then((result) => {
-      ok(result.session)
+      assert.ok(result.session)
     })
   )
 
   it('returns a cookie string that can be used for authenticated requests', () =>
     login(args.email, args.password, { host }).then((result) => {
-      ok(result.session)
+      assert.ok(result.session)
       return got(`${host}/_/users/me`, {
         headers: { cookie: result.cookie },
         json: true
       })
-    }).then(({ body }) => {
-      ok(body.data[0].id)
+    }).then((response) => {
+      assert.ok(response.body.data[0].id)
     })
   )
 
   it('can optionally retrieve an auth token', () =>
     login(args.email, args.password, { host, authToken: true }).then((result) => {
-      ok(result.session)
-      eq(typeof result.token, 'string')
+      assert.ok(result.session)
+      assert.strictEqual(typeof result.token, 'string')
     })
   )
 
   it('can retrieve auth tokens for guest users', () =>
     login.guest({ host, authToken: true }).then((result) => {
-      eq(typeof result.token, 'string')
+      assert.strictEqual(typeof result.token, 'string')
     })
   )
 
@@ -69,6 +71,6 @@ describe('plug-login', function () {
     login.user(args.email, args.password, {
       host,
       _simulateMaintenance: true
-    }).then(fail, ok)
+    }).then(assert.fail, assert.ok)
   )
 })