starting node forever script with PORT=XXXX

when running node in command over a specific port, I'd start the app this way:

PORT=1234 node app.js

how do I pass the port to the forever command? no matter what I try, it seems to not want to work.

I've tried:

• passing the port as an arg: forever start app.js 1234
• passing the port declaration as an arg: forever start app.js PORT=1234

PORT=1234 forever start app.js