Strange, I'll take another look

[2.0.0] ~ $ irb
2.0.0p195 :001 > YAML
NameError: uninitialized constant YAML
	from (irb):1
	from /Users/will/.rvm/rubies/ruby-2.0.0-p195/bin/irb:16:in `<main>'
2.0.0p195 :002 > require 'yaml'
 => true 
2.0.0p195 :003 > YAML
 => Psych