{$threadfields_display} formatting error in 1.8.4

[puritas]

I'm sure it's a really obvious answer I'll kick myself for, but after a bit of poking around I'm no closer to a solution so hoping someone can help-

The {$threadfields_display} in showthread throws the post columns way off (width drops to about 50%) if there's xthreads fields to display.

Where can I fix this?