Facebook Graph API SSL

I am trying to post to a facebook fan page wall using fb_graph 1.3.9 gem in ruby. That is working fine on a ubuntu box but not on FreeBSD

I receive the error below:

Got an error: SSL Verification failed -- Preverify: false, Error: unable to get local issuer certificate (20)

Any idea h开发者_如何学Cow to solve that problem?