diff --git a/Packages/Cartesian_kernel/include/CGAL/cartesian_classes.h b/Packages/Cartesian_kernel/include/CGAL/cartesian_classes.h
index d0a414bef62..a3b962a1267 100644
--- a/Packages/Cartesian_kernel/include/CGAL/cartesian_classes.h
+++ b/Packages/Cartesian_kernel/include/CGAL/cartesian_classes.h
@@ -56,6 +56,7 @@ template < class R, class T = typename R::Rep_tag > class Segment_3;
 template < class R, class T = typename R::Rep_tag > class Triangle_3;
 template < class R, class T = typename R::Rep_tag > class Tetrahedron_3;
 template < class R, class T = typename R::Rep_tag > class Iso_cuboid_3;
+template < class R, class T = typename R::Rep_tag > class Sphere_3;
 template < class R, class T = typename R::Rep_tag > class Aff_transformation_3;
 
 template < class R > class PointCd;
@@ -95,6 +96,7 @@ template < class R > class SegmentC3;
 template < class R > class TriangleC3;
 template < class R > class TetrahedronC3;
 template < class R > class Iso_cuboidC3;
+template < class R > class SphereC3;
 template < class R > class Aff_transformationC3;
 
 template < class R > class PointCd;