The parenthesis don't grow in this example: \input luaotfload.sty \font\test={name:XITS Math:mode=base;script=math} at 10pt %\font\test="[xits-math.otf]:script=math" at 10pt % for xetex \textfont0=\test $$ a \overwithdelims() b $$ \bye -- Khaled Hosny Arabic localiser and member of Arabeyes.org team Free font developer