diff --git a/.travis.yml b/.travis.yml
index e9e5c0e183..77e3c6662f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -35,6 +35,7 @@ before_script:
   - echo "USE mysql;\nGRANT ALL PRIVILEGES ON \`test_frappe\`.* TO 'test_frappe'@'localhost';\n" | mysql -u root -ptravis
   
   - cd ~/frappe-bench
+  - npm install babel-core less chokidar babel-preset-es2015 babel-preset-es2016 babel-preset-es2017 babel-preset-babili
   - bench use test_site
   - bench reinstall --yes
   - bench start &
diff --git a/frappe/build.js b/frappe/build.js
index e0b0a5f8db..4d14b933c5 100644
--- a/frappe/build.js
+++ b/frappe/build.js
@@ -24,7 +24,7 @@ const build_map = make_build_map();
 // command line args
 const action = process.argv[2] || '--build';
 
-if (!['--build', '--watch'].includes(action)) {
+if (['--build', '--watch'].indexOf(action) === -1) {
 	console.log('Invalid argument: ', action);
 	return;
 }
diff --git a/frappe/build.py b/frappe/build.py
index 56339f7c76..9e7f928d03 100644
--- a/frappe/build.py
+++ b/frappe/build.py
@@ -31,7 +31,7 @@ def bundle(no_compress, make_copy=False, verbose=False):
 	make_asset_dirs(make_copy=make_copy)
 
 	# new nodejs build system
-	command = 'node ../apps/frappe/frappe/build.js --build'
+	command = 'node --use_strict ../apps/frappe/frappe/build.js --build'
 	if not no_compress:
 		command += ' --minify'
 	subprocess.call(command.split(' '))
@@ -42,7 +42,7 @@ def watch(no_compress):
 	"""watch and rebuild if necessary"""
 
 	# new nodejs file watcher
-	command = 'node ../apps/frappe/frappe/build.js --watch'
+	command = 'node --use_strict ../apps/frappe/frappe/build.js --watch'
 	subprocess.call(command.split(' '))
 
 	# setup()