diff --git a/Gemfile b/Gemfile
index 9c1787272dc..cd8ce57875f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -14,6 +14,7 @@ group :development do
   gem 'rb-fsevent', '~> 0.9'
   gem 'stringex', '~> 1.4.0'
   gem 'liquid', '~> 2.3.0'
+  gem 'directory_watcher', '1.4.1'
 end
 
 gem 'sinatra', '~> 1.4.2'