diff --git a/Packages/Kernel_23/include/CGAL/Kernel/function_objects.h b/Packages/Kernel_23/include/CGAL/Kernel/function_objects.h
index 100d1abb656..5856277b78d 100644
--- a/Packages/Kernel_23/include/CGAL/Kernel/function_objects.h
+++ b/Packages/Kernel_23/include/CGAL/Kernel/function_objects.h
@@ -27,6 +27,8 @@
 #include <CGAL/Bbox_3.h>
 #include <CGAL/Kernel/Cartesian_coordinate_iterator_2.h>
 #include <CGAL/Kernel/Cartesian_coordinate_iterator_3.h>
+#include <CGAL/squared_distance_2.h>
+#include <CGAL/squared_distance_3.h>
 
 CGAL_BEGIN_NAMESPACE