ruby can't find readline on OS X 10.6

I'm running ruby 1.9.2 on OS X 10.6, and开发者_如何学JAVA mostly things are working fine. But readline doesn't seem to be working, either in IRB or in the rails console. A few different posts suggested building readline as an extension, like this

cd <ruby-source-dir>/ext/readline
ruby extconf.rb
make
make install

So I did that, and here's what I get:

checking for tgetnum() in -lncurses... yes
checking for readline/readline.h... yes
checking for readline/history.h... yes
checking for readline() in -lreadline... no
checking for readline() in -ledit... no
checking for editline/readline.h... yes
checking for readline() in -ledit... no

and then

make: Nothing to be done for `all'

This makes me think it's not finding my readline install. Any ideas on how to get it to find readline?

I re-compiled readline and then tried the steps above again and everything worked fine. I think this may be because I had originally compiled readline for osx 10.5, when ruby was still 32 bits.