diff --git a/Mainpage.dox b/Mainpage.dox
index 3545d0b4a4f3356357af20fa4b2f3ab85fed2dfe..98afe2b575cf5940f42d45af74c74b78a5338424 100644
--- a/Mainpage.dox
+++ b/Mainpage.dox
@@ -76,6 +76,7 @@
     \li The \c dia diagram editor (http://www.gnome.org/projects/dia/)
     \li HTML \c tidy (http://tidy.sourceforge.net/)
     \li The \c xsltproc XSLT processor (http://xmlsoft.org/XSLT/xsltproc2.html)
+    \li The \c graphviz library (http://www.graphviz.org)
 
 
     The library is only tested with gcc-3.4 and 4.0 on Linux. On other POSIX platforms with a BSD