diff --git a/Cartesian_kernel/include/CGAL/Cartesian/function_objects.h b/Cartesian_kernel/include/CGAL/Cartesian/function_objects.h
index ac34f9564b1..bc8b47e102e 100644
--- a/Cartesian_kernel/include/CGAL/Cartesian/function_objects.h
+++ b/Cartesian_kernel/include/CGAL/Cartesian/function_objects.h
@@ -23,6 +23,8 @@
 #include <CGAL/constructions/kernel_ftC2.h>
 #include <CGAL/constructions/kernel_ftC3.h>
 #include <CGAL/Cartesian/solve_3.h>
+#include <CGAL/squared_distance_Point_3_Point_3.h>
+#include <CGAL/internal/squared_distance_utils_3.h>
 
 namespace CGAL {