How to see issues *without* label? No obvious way to negate a label filter.

I mark issues with the "FIXED" label, so I can come back later and review/test them to see if I actually fixed it. If it's fixed, I close it. Otherwise, I remove the "FIXED" label.

How do I see a list of issues not "FIXED"?

I tried the UI and fussing with the URL.

Did I miss something?