Trouble with ffi and multi arch lib

gistfile1.sh

#console output
$ ruby lib/hitt/sdk.rb 

/Users/nick/.rvm/gems/ruby-1.9.3-p0-perf/gems/ffi-1.0.12.rc1/lib/ffi/library.rb:121:in `block in ffi_lib': Could not open library 'lib/ext/libH-ITTSDK.so': dlopen(lib/ext/libH-ITTSDK.so, 5): no suitable image found.  Did find: (LoadError)
	lib/ext/libH-ITTSDK.so: unknown file type, first eight bytes: 0x21 0x3C 0x61 0x72 0x63 0x68 0x3E 0x0A
	from /Users/nick/.rvm/gems/ruby-1.9.3-p0-perf/gems/ffi-1.0.12.rc1/lib/ffi/library.rb:88:in `map'
	from /Users/nick/.rvm/gems/ruby-1.9.3-p0-perf/gems/ffi-1.0.12.rc1/lib/ffi/library.rb:88:in `ffi_lib'
	from lib/hitt/sdk.rb:5:in `<module:Sdk>'
	from lib/hitt/sdk.rb:3:in `<main>'

$ file lib/ext/libH-ITTSDK.so
lib/ext/libH-ITTSDK.so: Mach-O universal binary with 4 architectures
lib/ext/libH-ITTSDK.so (for architecture ppc):	current ar archive random library
lib/ext/libH-ITTSDK.so (for architecture i386):	current ar archive random library
lib/ext/libH-ITTSDK.so (for architecture ppc64):	current ar archive random library
lib/ext/libH-ITTSDK.so (for architecture x86_64):	current ar archive random library

sdk.rb

module Hitt::Sdk
  extend FFI::Library
  ffi_lib 'lib/ext/libH-ITTSDK.so'
  attach_function 'hitt_sdk_version', [:char, :uint], :int
end