Stack overflow without space between value and "kg"

Just hit this issue on OSX Lion running ruby 1.9.2 and ruby-units 1.4.2

irb(main):001:0> require 'rubygems'
=> false
irb(main):002:0> require 'ruby-units'
=> true
irb(main):003:0> Unit.new("63.5029318kg").convert_to("lbs")
SystemStackError: stack level too deep
    from /Users/admin/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/irb/workspace.rb:80
Maybe IRB bug!!
