[1.9] Can't run debugger

$ jruby -v --1.9 -d --debug -rdebug -e 0
jruby 1.6.0.RC1 (ruby 1.9.2 patchlevel 136) (2011-01-19 36b741d) (Java HotSpot(TM) 64-Bit Server VM 1.6.0_22) [darwin-x86_64-java]
Exception `LoadError' at /Users/asari/Development/src/jruby/lib/ruby/site_ruby/shared/Win32API.rb:2 - Win32API only supported on win32
Exception `LoadError' at org/jruby/RubyKernel.java:1050 - no such file to load -- continuation
org/jruby/RubyKernel.java:1050:in `require19': no such file to load -- continuation (LoadError)
	from /Users/asari/Development/src/jruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:29:in `require'
	from /Users/asari/Development/src/jruby/lib/ruby/1.9/debug.rb:5:in `(root)'