parse-server: Can't connect to MongoDB via SSL and certificate

I am trying to run a local parse-server for development that connects to the hosted mongoDB instance on compose.io via SSL.

Compose.io provides a custom SSL certificate. I can successfully connect via mongo --ssl aws....com:10637/dbname -u <user> -p <password> --sslCAFile=compose_io.pem

However, if I specify the URL in the parse server config file with ssl=true I am getting the following error message at the console when an app (e.g. dashboard) tries to connect:

Uncaught internal server error. { [MongoError: unable to verify the first certificate]
  name: 'MongoError',
  message: 'unable to verify the first certificate' } Error: unable to verify the first certificate
    at Error (native)
    at TLSSocket.<anonymous> (_tls_wrap.js:1057:38)
    at emitNone (events.js:80:13)
    at TLSSocket.emit (events.js:179:7)
    at TLSSocket._init.ssl.onclienthello.ssl.oncertcb.TLSSocket._finishInit (_tls_wrap.js:596:8)
    at TLSWrap.ssl.onclienthello.ssl.oncertcb.ssl.onnewsession.ssl.onhandshakedone (_tls_wrap.js:428:38)

I found this article on compose.io regarding SSL connections: https://www.compose.io/articles/one-missing-key-and-how-it-broke-node-js-and-mongodb/

I can’t seem to find though options to specify the certificate in the parse-server config. Trusting the certificate in the OSX keychain doesn’t help either.

What am I missing?