diff --git a/doc/Doxyfiles/doxyfile.cmake b/doc/Doxyfiles/doxyfile.cmake
index c0b7e13de..07f08b056 100644
--- a/doc/Doxyfiles/doxyfile.cmake
+++ b/doc/Doxyfiles/doxyfile.cmake
@@ -37,7 +37,6 @@ IDL_PROPERTY_SUPPORT   = YES
 DISTRIBUTE_GROUP_DOC   = NO
 SUBGROUPING            = YES
 TYPEDEF_HIDES_STRUCT   = NO
-SYMBOL_CACHE_SIZE      = 0
 #---------------------------------------------------------------------------
 # Build related configuration options
 #---------------------------------------------------------------------------
@@ -198,8 +197,6 @@ MAN_LINKS              = NO
 #---------------------------------------------------------------------------
 GENERATE_XML           = NO
 XML_OUTPUT             = xml
-XML_SCHEMA             =
-XML_DTD                =
 XML_PROGRAMLISTING     = YES
 #---------------------------------------------------------------------------
 # configuration options for the AutoGen Definitions output
@@ -239,7 +236,6 @@ CLASS_DIAGRAMS         = YES
 MSCGEN_PATH            =
 HIDE_UNDOC_RELATIONS   = YES
 HAVE_DOT               = YES
-DOT_FONTNAME           = FreeSans
 DOT_FONTSIZE           = 10
 DOT_FONTPATH           =
 CLASS_GRAPH            = YES
diff --git a/doc/Doxyfiles/openthreads.doxyfile.cmake b/doc/Doxyfiles/openthreads.doxyfile.cmake
index 1955bf642..d53287f44 100644
--- a/doc/Doxyfiles/openthreads.doxyfile.cmake
+++ b/doc/Doxyfiles/openthreads.doxyfile.cmake
@@ -37,7 +37,6 @@ IDL_PROPERTY_SUPPORT   = YES
 DISTRIBUTE_GROUP_DOC   = NO
 SUBGROUPING            = YES
 TYPEDEF_HIDES_STRUCT   = NO
-SYMBOL_CACHE_SIZE      = 0
 #---------------------------------------------------------------------------
 # Build related configuration options
 #---------------------------------------------------------------------------
@@ -183,8 +182,6 @@ MAN_LINKS              = NO
 #---------------------------------------------------------------------------
 GENERATE_XML           = NO
 XML_OUTPUT             = xml
-XML_SCHEMA             =
-XML_DTD                =
 XML_PROGRAMLISTING     = YES
 #---------------------------------------------------------------------------
 # configuration options for the AutoGen Definitions output
@@ -224,7 +221,6 @@ CLASS_DIAGRAMS         = YES
 MSCGEN_PATH            =
 HIDE_UNDOC_RELATIONS   = YES
 HAVE_DOT               = YES
-DOT_FONTNAME           = FreeSans
 DOT_FONTSIZE           = 10
 DOT_FONTPATH           =
 CLASS_GRAPH            = YES