Well that was an easy fix. Seemed so strange that I thought it had to be a worse bug, but it's simply this: Use @ for instance variables in the to_yaml_properties method. Remember that! ;-) Cause if you don't it oddly cuts off the first letter of each varaible name --weird. def to_yaml_properties ['@key','@name','@version', ...] end NOT def to_yaml_properties ['key','name','version', ... ] end -t0