diff --git a/make.sh b/make.sh
index e83dcebde8b..312f8a9d8e1 100755
--- a/make.sh
+++ b/make.sh
@@ -13,6 +13,7 @@ npm run concat-docs-md &&
 
 mv js/CONTENT.md source/index.html.md &&
 
+gem install bundler &&
 bundle install &&
 bundle exec middleman build &&
 mv build ./mjml-doc &&