How to set upstream port

I’m writing some tests for a Worker.
I wrote a very basic server that will serve some pages the worker needs to transform.
I’m running

wragler dev --host http://localhost:8080 --upstream-protocol http --env development

If I’m understanding this correctly, if if do a

fetch(request);

I should be fetching the host set with the --host flag. My issue is that it seems to be dropping the port, and this make the test harder to be run in other development environments.

Is there some way to set the upstream port?