diff --git a/Three/doc/Three/Doxyfile.in b/Three/doc/Three/Doxyfile.in
index f13e096afeb..508b7cd3097 100644
--- a/Three/doc/Three/Doxyfile.in
+++ b/Three/doc/Three/Doxyfile.in
@@ -1,11 +1,9 @@
 @INCLUDE = ${CGAL_DOC_PACKAGE_DEFAULTS}
 PROJECT_NAME = "CGAL ${CGAL_CREATED_VERSION_NUM} - Three"
-INPUT        = ${CMAKE_SOURCE_DIR}/Three/doc/Three/ \
-               ${CMAKE_SOURCE_DIR}/Three/include/CGAL/Three/ \
-               ${CMAKE_SOURCE_DIR}/Polyhedron/demo/Polyhedron/Scene.h \
-               ${CMAKE_SOURCE_DIR}/Polyhedron/demo/Polyhedron/Viewer.h \
-               ${CMAKE_SOURCE_DIR}/Polyhedron/demo/Polyhedron/MainWindow.h \
-               ${CMAKE_SOURCE_DIR}/Polyhedron/demo/Polyhedron/Polyhedron_demo.h \
+INPUT        += ${CGAL_Polyhedron_DEMO_DIR}/Polyhedron/Scene.h \
+                ${CGAL_Polyhedron_DEMO_DIR}/Polyhedron/Viewer.h \
+                ${CGAL_Polyhedron_DEMO_DIR}/Polyhedron/MainWindow.h \
+                ${CGAL_Polyhedron_DEMO_DIR}/Polyhedron/Polyhedron_demo.h \
                
 EXAMPLE_PATH = ${CGAL_PACKAGE_DIR}/demo