Firefox - disabling location bar searching?

Scenario: a disk in my NAS just died so the web interface for it falls over. If I try to access it as a local http://somename/ while it is down, firefox automagically gives up after a while and takes me to instead. Any way to turn this off?

I tried changing:
but neither of those seem to be it.

At least IE gives you a big button to turn off this type of searching…

Edit: finally found browser.fixup.alternate.enabled might be the one I’m looking for (how intuitive) but now the NAS is back up I can’t test it yet…