diff --git a/doc/doxygen.cfg b/doc/doxygen.cfg
index 1a53af56..42b63394 100644
--- a/doc/doxygen.cfg
+++ b/doc/doxygen.cfg
@@ -227,8 +227,6 @@ MAN_LINKS              = NO
 #---------------------------------------------------------------------------
 GENERATE_XML           = NO
 XML_OUTPUT             = xml
-XML_SCHEMA             =
-XML_DTD                =
 XML_PROGRAMLISTING     = YES
 #---------------------------------------------------------------------------
 # configuration options related to the DOCBOOK output