diff --git a/vagrant/lib/forklift/box_distributor.rb b/vagrant/lib/forklift/box_distributor.rb
index ba56dd631..3850673ac 100644
--- a/vagrant/lib/forklift/box_distributor.rb
+++ b/vagrant/lib/forklift/box_distributor.rb
@@ -5,7 +5,7 @@
 module Forklift
   class BoxDistributor
 
-    VAGRANTFILE_API_VERSION = '2'
+    VAGRANTFILE_API_VERSION = '2'.freeze
 
     def initialize(boxes)
       @ansible_groups = {}