Hi Hans and Mikael, I think there is an issue with the size of math fonts in \frac when used in math alignments, as it is is shown in the following example. %% begin bug-mathalignment.tex \definemathmatrix[alignedcases] [align={1:right,2:left,3:left}, distance=3pt, left={\left\{}, right={\right.}, style=\displaystyle] \starttext Consider this \placeformula \startformula \startalignedcases \NC - \Delta u \NC = 0 \NC \qquad\text{in }\, \Omega \NR \NC \frac{\partial u}{\partial {\bi n}} \NC = V u + \phi \NC \qquad\text{on }\, \partial\Omega. \NR \stopalignedcases \stopformula or this (with\type{\displaystyle} added) \placeformula \startformula \startalignedcases \NC - \Delta u \NC = 0 \NC \qquad\text{in }\, \Omega \NR \NC \displaystyle\frac{\partial u}{\partial {\bi n}} \NC = V u + \phi \NC \qquad\text{on }\, \partial\Omega. \NR \stopalignedcases \stopformula Actually, one should have this \startformula \frac{\partial u}{\partial {\bi n}} = V u + \phi \qquad\text{on }\, \partial\Omega. \stopformula If one adds \type{\displaystyle} both to the numerator and denominator of \type{\frac}, the result is correct: \placeformula \startformula \startalignedcases \NC - \Delta u \NC = 0 \NC \qquad\text{in }\, \Omega \NR \NC \frac{\displaystyle\partial u}{\displaystyle\partial {\bi n}} \NC = V u + \phi \NC \qquad\text{on }\, \partial\Omega. \NR \stopalignedcases \stopformula \stoptext %% end bug-mathalignment.tex