See this MWE: \documentclass[full]{l3doc} \title{An \pkg{l3doc} bug} \author{Joel C. Salomon} \begin{document} \maketitle \begin{documentation} \begin{function}{\some_function_with_a_very_long_name:nnnnn} \begin{syntax} "\some_function_with_a_very_long_name:nnnnn" <first argument> <second argument> <third argument> <fourth argument> <fifth argument> "\some_function_with_a_very_long_name:nnnnn" <first argument> <second argument> <third argument> <fourth argument> <fifth argument> "\some_function_with_a_very_long_name:nnnnn" % <first argument> <second argument> <third argument> <fourth argument> % <fifth argument> \end{syntax} Notice how the first line is very very long in the source, but when I split it up, the split is reflected in the output. Adding comments just makes things worse. \end{function} \end{documentation} \end{document}