NPM Install Tunneling Socket Error

ENV
OSX 10.11.6
Docker 1.12.3
HTTP Proxy Settings - Yes, I am behind a corporate proxy; The settings have been configured to match the host environment where things are working fine.

ISSUE
After building an image and attempting to install NPM dependencies, I obtain the following error:

Error: tunneling socket could not be established, cause=write EPROTO 140377978709824:error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol:…/deps/openssl/openssl/ssl/s23_clnt.c:794:

Any suggestions? Thank you in advance!

Resolved: I didn’t specify a host:container port mapping.