Hi, I think I found the bug that made me send a "false positive" a few days ago. Looks like something messes up with metafun odd function. This snippet of code: \starttext \startMPpage path p;p:=origin--(20,20); draw p; draw p reflectedabout ((10,10),(10,-10)) withcolor red; for i=1 upto 2: if odd i: draw p yshifted 20 withcolor green; else: draw p xshifted 20 withcolor blue; fi; endfor; %draw (0,0)--(20,20) withcolor red; \stopMPpage \stoptext does not compile as I would expect it: no green line is drawn (but there is an output). I hope I did not miss something and won't waste your time. This appeared at least in 2020.12.30 16:45 version (I don't update often enough to give better hints) Best regards, Damien Thiriet