Error found in RubyGems
 
C:\Program Files (x86)\IronRuby 1.0\bin>irb
irb(main):001:0> Dir['ir.exe', 'ir64.exe']
=> ["ir.exe", "ir64.exe"]
irb(main):002:0> exit
 
C:\Program Files (x86)\IronRuby 1.0\bin>rbr
IronRuby 0.9.5.0 on .NET 2.0.50727.4927
Copyright (c) Microsoft Corporation. All rights reserved.
 

Dir['ir.exe', 'ir64.exe']
(ir):1: can't convert String into Fixnum (TypeError)
 
Dir['ir.exe']
=> ["ir.exe"]
Dir['ir.exe', nil, nil, nil]
(ir):1: wrong number of arguments (4 for 2) (ArgumentError)