diff --git a/Polygon/doc/Polygon/Doxyfile.in b/Polygon/doc/Polygon/Doxyfile.in
index f4a3edd012e..2102a8684cd 100644
--- a/Polygon/doc/Polygon/Doxyfile.in
+++ b/Polygon/doc/Polygon/Doxyfile.in
@@ -3,7 +3,7 @@
 PROJECT_NAME = "CGAL ${CGAL_DOC_VERSION} - 2D Polygons"
 EXAMPLE_PATH = ${CGAL_PACKAGE_DIR}/examples \
                ${CGAL_Stream_support_EXAMPLE_DIR}
-
+INPUT += ${CGAL_PACKAGE_INCLUDE_DIR}/CGAL
 
 EXTRACT_ALL                =  false
 HIDE_UNDOC_MEMBERS         =  true