How to safely create file in bash

I have a script that creates a temporary file as a flag to guard against the script being run simultaneously. Currently it uses tempfile, e.g.

if ! tempfile -n /tmp/updating > /dev/null; then
	echo 'Another synchronization is currently running' >&2
	exit 1
fi

The tempfile program is now deprecated, it suggests using mktemp instead, but mktemp doesn't seem to have an option similar to -n. I'm using Ubuntu 21.04. So how should I safely create a flag file?