entar instalar a pg gem me dá erro

Estou usando o Ruby 1.9.3-p125 construído usando rbenv / ruby-build. Instalei o PostgreSQL usando o instalador de um clique. Consigo me conectar ao banco de dados usando o pgAdmin. Estou ficando sem ideias.

% gem install pg                                                                                                                                                                                                      ~
Building native extensions.  This could take a while...
ERROR:  Error installing pg:
    ERROR: Failed to build gem native extension.

        /Users/sandropadin/.rbenv/versions/1.9.3-p125/bin/ruby extconf.rb
checking for pg_config... yes
Using config values from /usr/bin/pg_config
checking for libpq-fe.h... yes
checking for libpq/libpq-fs.h... yes
checking for pg_config_manual.h... yes
checking for PQconnectdb() in -lpq... yes
checking for PQconnectionUsedPassword()... yes
checking for PQisthreadsafe()... yes
checking for PQprepare()... yes
checking for PQexecParams()... yes
checking for PQescapeString()... yes
checking for PQescapeStringConn()... yes
checking for PQgetCancel()... yes
checking for lo_create()... yes
checking for pg_encoding_to_char()... yes
checking for pg_char_to_encoding()... yes
checking for PQsetClientEncoding()... yes
checking for rb_encdb_alias()... yes
checking for rb_enc_alias()... yes
checking for struct pgNotify.extra in libpq-fe.h... yes
checking for unistd.h... yes
checking for ruby/st.h... yes
creating extconf.h
creating Makefile

make
compiling pg.c
compiling pg_connection.c
pg_connection.c: In function ‘pgconn_wait_for_notify’:
pg_connection.c:1986: warning: ‘rb_thread_select’ is deprecated (declared at /Users/sandropadin/.rbenv/versions/1.9.3-p125/include/ruby-1.9.1/ruby/intern.h:379)
pg_connection.c: In function ‘pgconn_block’:
pg_connection.c:2512: warning: ‘rb_thread_select’ is deprecated (declared at /Users/sandropadin/.rbenv/versions/1.9.3-p125/include/ruby-1.9.1/ruby/intern.h:379)
compiling pg_result.c
linking shared-object pg_ext.bundle
ld: in /usr/local/lib/libssl.0.9.8.dylib, missing required architecture x86_64 in file for architecture x86_64
collect2: ld returned 1 exit status
make: *** [pg_ext.bundle] Error 1


Gem files will remain installed in /Users/sandropadin/.rbenv/versions/1.9.3-p125/lib/ruby/gems/1.9.1/gems/pg-0.13.2 for inspection.
Results logged to /Users/sandropadin/.rbenv/versions/1.9.3-p125/lib/ruby/gems/1.9.1/gems/pg-0.13.2/ext/gem_make.out