diff --git a/develop/doxygen/doxygen.desc b/develop/doxygen/doxygen.desc
index b7339412a..3dd576a18 100644
--- a/develop/doxygen/doxygen.desc
+++ b/develop/doxygen/doxygen.desc
@@ -41,6 +41,7 @@
 [U] http://www.stack.nl/~dimitri/doxygen/
 
 [C] extra/development
+[F] X11R6
 
 [L] GPL
 [S] Stable