diff --git a/cli.js b/cli.js
index 26de9bf..dda46cc 100755
--- a/cli.js
+++ b/cli.js
@@ -1,5 +1,7 @@
 #!/usr/bin/env node
 
+'use strict';
+
 const spawn = require('child_process').spawn;
 const hugo = require('.');
 const input = process.argv.slice(2);
diff --git a/index.js b/index.js
index 77e8c70..4591f10 100644
--- a/index.js
+++ b/index.js
@@ -1 +1,3 @@
+'use strict';
+
 module.exports = require('./lib')(process.cwd()).path();
diff --git a/lib/index.js b/lib/index.js
index 7a7de46..8da7443 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -1,3 +1,5 @@
+'use strict';
+
 const path = require('path');
 const BinWrapper = require('bin-wrapper');
 const pkgConf = require('pkg-conf');
diff --git a/lib/install.js b/lib/install.js
index 247d756..b3cd0ff 100644
--- a/lib/install.js
+++ b/lib/install.js
@@ -1,3 +1,5 @@
+'use strict';
+
 const path = require('path');
 const signale = require('signale');
 const bin = require('.');
diff --git a/package.json b/package.json
index 2a341fd..a617211 100644
--- a/package.json
+++ b/package.json
@@ -40,9 +40,6 @@
     "env": {
       "es6": true,
       "node": true
-    },
-    "parserOptions": {
-      "sourceType": "module"
     }
   }
 }
diff --git a/test/index.js b/test/index.js
index 1155d7c..f097b57 100644
--- a/test/index.js
+++ b/test/index.js
@@ -1,5 +1,7 @@
 /* eslint-env mocha */
 
+'use strict';
+
 const assert = require('assert');
 const binCheck = require('bin-check');
 const hugoBin = require('..');