diff --git a/examples/technical_report/Isabelle_DOF-Manual/document/lstisadof-manual.sty b/examples/technical_report/Isabelle_DOF-Manual/document/lstisadof-manual.sty
index d81005e..9c1589d 100755
--- a/examples/technical_report/Isabelle_DOF-Manual/document/lstisadof-manual.sty
+++ b/examples/technical_report/Isabelle_DOF-Manual/document/lstisadof-manual.sty
@@ -184,6 +184,7 @@
 \lstdefinestyle{lltx}{language=[AlLaTeX]TeX,
   ,basicstyle=\ttfamily%
   ,showspaces=false%
+  ,escapechar=ë
   ,showlines=false%
   ,morekeywords={newisadof}
  %  ,keywordstyle=\bfseries%