diff --git a/Doc/lectures.xml b/Doc/lectures.xml
index 283ba9604a3c51f1781f7e9d5a3eb4b1123f59df..14da972e03642febd08eaa1a6258a7cbfad1649a 100644
--- a/Doc/lectures.xml
+++ b/Doc/lectures.xml
@@ -96,7 +96,7 @@
         <caution>
           <para>Since <productname
           xlink:href="https://en.wikipedia.org/wiki/EPUB">Epub</productname>
-          readers do not (yet) support <xref linkend="glo_EPUB"/> 3.0 formulas
+          readers do not (yet) support <xref linkend="glo_EPUB"/> 3.0 both formulas
           and <xref linkend="glo_SVG"/> images have been converted to <xref
           linkend="glo_PNG"/> files. This may account for poor image
           quality.</para>