diff --git a/tools/build.js b/tools/build.js
index 16343df..feeeabc 100644
--- a/tools/build.js
+++ b/tools/build.js
@@ -9,7 +9,6 @@
 
 'use strict';
 
-const fs = require('fs');
 const del = require('del');
 const rollup = require('rollup');
 const babel = require('rollup-plugin-babel');