diff --git a/Convex_hull_2/demo/Convex_hull_2/Qt_widget_move_list_point.C b/Convex_hull_2/demo/Convex_hull_2/Qt_widget_move_list_point.C
index 2597419f8a9..fe3013b6428 100644
--- a/Convex_hull_2/demo/Convex_hull_2/Qt_widget_move_list_point.C
+++ b/Convex_hull_2/demo/Convex_hull_2/Qt_widget_move_list_point.C
@@ -17,6 +17,8 @@
 //
 // Author(s)     : Radu Ursu
 
+#include <CGAL/basic.h>
+
 #ifdef CGAL_USE_QT
 
 #include "Qt_widget_move_list_point.h"
diff --git a/Convex_hull_2/demo/Convex_hull_2/Qt_widget_toolbar.C b/Convex_hull_2/demo/Convex_hull_2/Qt_widget_toolbar.C
index 310e9c8ed77..70502cd60f9 100644
--- a/Convex_hull_2/demo/Convex_hull_2/Qt_widget_toolbar.C
+++ b/Convex_hull_2/demo/Convex_hull_2/Qt_widget_toolbar.C
@@ -17,6 +17,8 @@
 //
 // Author(s)     : Radu Ursu
 
+#include <CGAL/basic.h>
+
 #ifdef CGAL_USE_QT
 
 #include <CGAL/IO/Qt_widget.h>