Try this with both MRI and Jruby 1.1.6 (with active support 2.2.2) irb(main):004:0> require 'rubygems' => true irb(main):005:0> require 'activesupport' => true irb(main):006:0> YAML.load(YAML.dump(3.0)).eql?(3.0) => true MRI returns true, while JRuby returns false !!! The root cause is that JRuby is loading the yaml as irb(main):021:0> YAML.load(YAML.dump(3.0)) => #<YAML::PrivateType:0x18ad9a0 @value="3.0", @type_id="tag:yaml.org, 2002:float:Float"> instead of as 3.0 Has any bug been logged for this? I would have gone ahead and logged it, but I am unable to register on codehaus :(. For some wierd reason, I just can't get thru their capta!!! (another bug???). Would be great if someone could log this one as a bug or point me to an already logged bug or otherwise explain this behaviour. Pradeep