Missing / in factorio log path

[Wyrrrd]

When starting the Factorio server, I get a permission error syslogged after every line of log output:
Cannot open logfile for appending Factorio Server output: open /srv/factorioserverfactorio-server-console.log: permission denied

(I can verify that the logfile at /srv/factorioserver/factorio-server-console.log is not written and the expected file /srv/factorioserverfactorio-server-console.log does not exist.)

Running FSM 0.8.1 on Ubuntu 18.04.2 LTS