--- a/doc/doxygen_header.tex.in
+++ b/doc/doxygen_header.tex.in
@@ -79,6 +79,7 @@
 \renewcommand{\footrulewidth}{0.4pt}
 \renewcommand{\familydefault}{\sfdefault}
 \newcommand{\clearemptydoublepage}{\newpage{\pagestyle{empty}}}
+\newcommand{\+}{\discretionary{\mbox{\scriptsize$\hookleftarrow$}}{}{}}
 \hfuzz=15pt
 \setlength{\emergencystretch}{15pt}
 \hbadness=750
