diff --git a/Cartesian_kernel/include/CGAL/Cartesian/function_objects.h b/Cartesian_kernel/include/CGAL/Cartesian/function_objects.h
index 064d69088fc..1242bb48404 100644
--- a/Cartesian_kernel/include/CGAL/Cartesian/function_objects.h
+++ b/Cartesian_kernel/include/CGAL/Cartesian/function_objects.h
@@ -1764,10 +1764,10 @@ namespace CartesianKernelFunctors {
         // to avoid badly defined vectors with coordinates all close
         // to 0 when the plane is almost horizontal, we ignore the
         // smallest coordinate instead of always ignoring Z
-        if (a <= b && a <= c)
+        if (CGAL::possibly(a <= b && a <= c))
           return Vector_3(FT(0), -h.c(), h.b());
 
-        if (b <= a && b <= c)
+        if (CGAL::possibly(b <= a && b <= c))
           return Vector_3(-h.c(), FT(0), h.a());
 
         return Vector_3(-h.b(), h.a(), FT(0));