diff --git a/Algebraic_kernel_for_spheres/include/CGAL/Algebraic_kernel_for_spheres/internal_functions_on_roots_and_polynomials_1_3.h b/Algebraic_kernel_for_spheres/include/CGAL/Algebraic_kernel_for_spheres/internal_functions_on_roots_and_polynomials_1_3.h
index 671169da0fb..b9af328f14d 100644
--- a/Algebraic_kernel_for_spheres/include/CGAL/Algebraic_kernel_for_spheres/internal_functions_on_roots_and_polynomials_1_3.h
+++ b/Algebraic_kernel_for_spheres/include/CGAL/Algebraic_kernel_for_spheres/internal_functions_on_roots_and_polynomials_1_3.h
@@ -29,6 +29,8 @@ namespace CGAL {
     typedef typename AK::RT RT;
     typedef typename AK::FT FT;
     typedef typename AK::Root_for_spheres_2_3 Root_for_spheres_2_3;
+    CGAL_kernel_precondition(!(same_solutions<FT>(e1,e2) || same_solutions<FT>(e1,e3) ||
+                               same_solutions<FT>(e2,e3)));
     const FT &a1 = e1.a();
     const FT &a2 = e2.a();
     const FT &a3 = e3.a();