diff --git a/Boolean_set_operations_2/demo/Boolean_set_operations_2/boolean_operations_2_toolbar.C b/Boolean_set_operations_2/demo/Boolean_set_operations_2/boolean_operations_2_toolbar.C
index c41ea47a454..a4cf4d1ac31 100644
--- a/Boolean_set_operations_2/demo/Boolean_set_operations_2/boolean_operations_2_toolbar.C
+++ b/Boolean_set_operations_2/demo/Boolean_set_operations_2/boolean_operations_2_toolbar.C
@@ -17,6 +17,7 @@
 //
 // Author(s)     : Baruch Zukerman <baruchzu@post.tau.ac.il>
 
+#include <CGAL/basic.h>
 
 #ifdef CGAL_USE_QT