diff --git a/lib/vagrant/config/loader.rb b/lib/vagrant/config/loader.rb
index 0914b1eb2..8d1c85f6e 100644
--- a/lib/vagrant/config/loader.rb
+++ b/lib/vagrant/config/loader.rb
@@ -219,7 +219,7 @@ module Vagrant
         # Get the proper version loader for this version and load
         version_loader = @versions.get(version)
         raise KeyError,
-              "Failed to create loader for requested version: #{version}"
+              "Failed to create loader for requested version: #{version}" if version_loader.nil?
 
         begin
           version_config = version_loader.load(proc)