diff --git a/Isosurfacing_3/include/CGAL/Isosurfacing_3/Finite_difference_gradient_3.h b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Finite_difference_gradient_3.h
index 4895c8d721d..4893bf040be 100644
--- a/Isosurfacing_3/include/CGAL/Isosurfacing_3/Finite_difference_gradient_3.h
+++ b/Isosurfacing_3/include/CGAL/Isosurfacing_3/Finite_difference_gradient_3.h
@@ -99,6 +99,9 @@ public:
 
     const FT n = CGAL::approximate_sqrt(CGAL::square(gx) + CGAL::square(gy) + CGAL::square(gz));
 
+    if(is_zero(n))
+      return vector(0,0,0);
+
     return vector(gx / n, gy / n, gz / n);
   }
 };