Dear list, in this sample for underscore hyphenation (which comes from Hans), font expansion breaks char.width and displaces the underscore: \startluacode function document.addfunnyhyphen(tfmdata) local underscore = utf.byte("_") local char = tfmdata.characters[underscore] if not char then return end tfmdata.characters[0xFE000] = { width = 0, height = 0, depth = 0, commands = { { "right", -char.width }, { "down", char.depth }, { "slot", 1, underscore }, } } end utilities.sequencers.appendaction("aftercopyingcharacters", "after","document.addfunnyhyphen") \stopluacode \definehyphenationfeatures [underscore] [righthyphenchar="FE000] \setuphyphenation [method=traditional] \unexpanded\def\sha#1% {\begingroup\tt \sethyphenationfeatures[underscore]% #1% \endgroup} \definefontfeature[default][default][expansion=quality] \setupalign[hanging, hz] \definefontfamily[mainface][tt][Cousine][scale=0.85] \setupbodyfont[mainface] \starttext \hsize\zeropoint \sha{\dorecurse{25}{asdfasdfasdfaeasfae}} \stoptext I’m using latest from 2020.05.12 16:21. Have I hit a bug or am I missing something? Many thanks for your help, Pablo -- http://www.ousia.tk