diff --git a/lib/vagrant/cli.rb b/lib/vagrant/cli.rb
index 4158f16dd..0133daedd 100644
--- a/lib/vagrant/cli.rb
+++ b/lib/vagrant/cli.rb
@@ -54,7 +54,7 @@ module Vagrant
         # Add the available subcommands as separators in order to print them
         # out as well.
         keys = []
-        Vagrant.commands.each { |key, value| keys << key }
+        Vagrant.commands.each { |key, value| keys << key.to_s }
 
         keys.sort.each do |key|
           opts.separator "     #{key}"