How to connect to an Amazon PostgreSQL database using SSL

I’m trying to log into an Amazon PostgreSQL DBS using SSL. I have all credentials but my psql version doesn’t seem to support SSL. I’ve tried searching Postgres docs but all I see is how it has native support. Here’s my command and output. I’m running the psql command on a CentOS 6.5 box.

psql --host=XXXX.rds.XXXX.com  --sslmode=require --sslrootcert=rds-ssl-ca-cert.pem 
--port=XXXX --username=XXXXX --password --dbname=XXXX

Response:

psql: unrecognized option '--sslmode=require'

So my question is, how do I install a psql client that supports SSL. I don’t need the full blown DB support, just the connector, psql.

Thanks

I should add that I’m trying to follow these instructions.
http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/CHAP_PostgreSQL.html#PostgreSQL.Concepts.General.SSL