What is the preferred way of fixing an overfull hbox problem when it complains about the chapter title.
MWE (complains about the \chapter{Chapter title}
line):
\documentclass[12pt,twoside]{book}
\textwidth 150mm
\usepackage[Bjornstrup]{fncychap}
\oddsidemargin 5mm
\evensidemargin 5mm
\topmargin 0mm
\headheight 0mm
\textheight 225mm
\begin{document}
\chapter{Chapter title}
lorem impsum.
\end{document}
Looking at the different threads on TeX.se I could not find the answer. Since I have many chapters, I would appreciate a more general solution.