diff --git a/doc/physics2.tex b/doc/physics2.tex
index 02458f4..6dfcf23 100644
--- a/doc/physics2.tex
+++ b/doc/physics2.tex
@@ -495,7 +495,7 @@ \subsection{The \modu{xmat} module --- matrices with formatted entries}
 \opt{format} should be only used in the optional argument of the
 \cs{xmat} command.
 
-\section{The ``legacy'' modules}
+\section{The \texorpdfstring{``legacy''}{“legacy”} modules}
 The legacy modules have similar names like \meta{module}\opt{.legacy}. Most of
 them are designed to provide solutions to maintain documents written with the
 legacy \pkg{physics} package. It's not suggested to use them in a new document.