I think I've found my problem (finally). The problem is in 'type-enc.tex' I referred to the standard text fonts for Fourier-Math-Letters and Fourier-Math-Letters-Bold instead of the true math fonts. I believe this is how ConTeXt is configured in its default... In any case, 'type-enc.tex' should contain: \starttypescript [math] [fourier] [default,ec] \definefontsynonym [Fourier-Math-Letters] [futmi] [encoding=ec] \definefontsynonym [Fourier-Math-Letters-Italic] [futmii] \definefontsynonym [Fourier-Math-Symbols] [futsy] \definefontsynonym [Fourier-Math-Extension] [fourier-mex] \stoptypescript \starttypescript [boldmath,bfmath] [fourier] [default,ec] \definefontsynonym [Fourier-Math-Letters-Bold] [futmib] [encoding=ec] \definefontsynonym [Fourier-Math-Letters-Italic-Bold] [futmiib] \definefontsynonym [Fourier-Math-Symbols] [futsy] \definefontsynonym [Fourier-Math-Extension] [fourier-mex] \stoptypescript The substitution problem can be seen quite clearly from: \starttext \loadmapfile[fourier] % Original definition \definefontsynonym [Fourier-Math-Letters] [futr8t] \definefontsynonym [Fourier-Math-Letters-Italic] [futmii] \definefontsynonym [Fourier-Math-Letters-Bold] [futb8t] \definefontsynonym [Fourier-Math-Letters-Italic-Bold] [futmiib] \definefontsynonym [Fourier-Math-Symbols] [futsy] \definefontsynonym [Fourier-Math-Extension] [fourier-mex] \section{Fourier-Math-Letters} \showfont[Fourier-Math-Letters] \section{Fourier-Math-Letters-Italic} \showfont[Fourier-Math-Letters-Italic] \section{Fourier-Math-Letters-Bold} \showfont[Fourier-Math-Letters-Bold] \section{Fourier-Math-Letters-Italic-Bold} \showfont[Fourier-Math-Letters-Italic-Bold] \section{Fourier-Math-Symbols} \showfont[Fourier-Math-Symbols] \section{Fourier-Math-Extension} \showfont[Fourier-Math-Extension] % What about these fonts? \section{futmi} \showfont[futmi] \section{futmib} \showfont[futmib] \stoptext Many thanks to those who replied, Randall