diff --git a/lib/vagrant/config/vm.rb b/lib/vagrant/config/vm.rb
index 814534378..63e003a94 100644
--- a/lib/vagrant/config/vm.rb
+++ b/lib/vagrant/config/vm.rb
@@ -103,6 +103,8 @@ module Vagrant
                        :path => options[:hostpath])
           end
         end
+
+        errors.add("vagrant.config.vm.boot_mode_invalid") if ![:vrdp, :gui].include?(boot_mode.to_sym)
       end
     end
   end
diff --git a/templates/locales/en.yml b/templates/locales/en.yml
index 5e3b970a9..eb2c4a937 100644
--- a/templates/locales/en.yml
+++ b/templates/locales/en.yml
@@ -101,6 +101,7 @@ en:
         private_key_missing: "`private_key_path` file must exist: %{path}"
       vm:
         shared_folder_hostpath_missing: "Shared folder host path for '%{name}' doesn't exist: %{path}"
+        boot_mode_invalid: "Boot mode must be one of: vrdp or gui"
 
 #-------------------------------------------------------------------------------
 # Translations for commands. e.g. `vagrant x`