Hi, the \fenced command doesn’t decrement the nesting counter at the end. \unexpanded\def\math_fenced_fenced[#1]#2% {\math_fenced_fenced_start{#1}% #2% \math_fenced_right \stopusemathstyleparameter - \endgroup} + \endgroup + \advance\c_math_fenced_nesting\minusone} Wolfgang