diff --git a/plugins/synced_folders/rsync/command/rsync_auto.rb b/plugins/synced_folders/rsync/command/rsync_auto.rb
index 161fbf184..3d3cd226c 100644
--- a/plugins/synced_folders/rsync/command/rsync_auto.rb
+++ b/plugins/synced_folders/rsync/command/rsync_auto.rb
@@ -2,6 +2,7 @@ require "log4r"
 require 'optparse'
 require "thread"
 
+require "listen"
 
 require "vagrant/action/builtin/mixin_synced_folders"
 require "vagrant/util/busy"