diff --git a/Gruntfile.js b/Gruntfile.js
index 42b8dad..1a929cf 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -1,4 +1,6 @@
 // Copyright 2020, University of Colorado Boulder
 
+/* eslint-env node */
+
 // use chipper's gruntfile
 module.exports = require( '../chipper/js/grunt/Gruntfile.js' );
diff --git a/phettest/index-server.js b/phettest/index-server.js
index ff7528e..2fe0427 100644
--- a/phettest/index-server.js
+++ b/phettest/index-server.js
@@ -1,5 +1,7 @@
 // Copyright 2016, University of Colorado Boulder
 
+/* eslint-env node */
+
 const http = require( 'http' );
 const spawn = require( 'child_process' ).spawn; // eslint-disable-line
 const path = require( 'path' );