Unfortunately a small error crept into this file in the release last week. calc.dtx has been updated on ftp.tex.ac.uk. Other ctan sites and mirrors will update in due course. If you have this version of calc: [1998/06/07 v4.1a Infix arithmetic (KKT,FJ)] Please obtain a new calc.dtx from tex-archive/macros/latex/packages/tools/calc.dtx which should have the following version info: [1998/07/07 v4.1b Infix arithmetic (KKT,FJ)] and then regenerate calc.sty by running tex on tools.ins. Sorry for this inconvenience and special apologies to Kresten Krab Thorup and Frank Jensen who were responsible for this package, but not responsible for introducing this bug. David Carlisle LaTeX3 Project