How to programmatically generate a newline using scribble-slideshow?

I am generating code listings in Scribble that I highlight myself. Example: todo list

I have been using (make-element 'newline '()) to generate newlines which work when rendered to HTML, but when shown in slideshow, they don't appear.

E.g. I'd expect the a and b to be separated by a line break in the following snippet, but they are not.

#lang scribble-slideshow
@(require scribble/core scribble/base scribble/manual)


@(list "a" (make-element 'newline '()) "b")

If I change to #lang scribble/manual, the line break is shown as expected:

Rendered to HTML

How can I get generated line breaks to work in scribble-slideshow?