# ToC chapter number width & memoir class

I've changed the chapter numbering to Roman, and now I want to increase the number width in the table of contents in order to avoid overlapping with chapter titles.

The usual trick

\setlength{\cftchapnumwidth}{2em}


with tocloft package doesn't work here because of the conflict with the class memoir. And when I try

\DisemulatePackage{tocloft}


a lot of errors appear.

How can I do ?

Here's a MWE :

\documentclass[a4paper,11pt,twoside]{memoir}

\makeatletter
\renewcommand \thechapter{\@Roman\c@chapter}
\makeatother

\begin{document}
\tableofcontents*
\chapter{Chapter one}
\chapter{Chapter two}
\chapter{Chapter three}
\end{document}


You need to set the length \cftchapternumwidth:

\documentclass{memoir}

\renewcommand{\thechapter}{\Roman{chapter}}
\setlength{\cftchapternumwidth}{5em}

\begin{document}

\tableofcontents*
\chapter{Chapter one}
\chapter{Chapter two}
\chapter{Chapter three}

\end{document}