diff --git a/src/cgalutils-tess.cc b/src/cgalutils-tess.cc
index e230e9db..7a8b80f0 100644
--- a/src/cgalutils-tess.cc
+++ b/src/cgalutils-tess.cc
@@ -107,6 +107,8 @@ namespace CGALUtils {
 		else {
 			// Calculate best guess at face normal using Newell's method
 			CGAL::normal_vector_newell_3(polygons.front().begin(), polygons.front().end(), normalvec);
+			double sqrl = normalvec.squared_length();
+			if (sqrl > 0.0) normalvec = normalvec / sqrt(sqrl);
 		}
 
 		// Pass the normal vector to the (undocumented)
diff --git a/src/cgalutils.cc b/src/cgalutils.cc
index 5d951936..7003eb3e 100644
--- a/src/cgalutils.cc
+++ b/src/cgalutils.cc
@@ -917,10 +917,13 @@ namespace CGALUtils {
 				 and let the tessellater deal with the holes, and then
 				 just output the resulting 3d triangles*/
 
-			CGAL::Vector_3<CGAL_Kernel3> nvec = plane.orthogonal_vector();
-			K::Vector_3 normal(CGAL::to_double(nvec.x()), CGAL::to_double(nvec.y()), CGAL::to_double(nvec.z()));
+			// We cannot trust the plane from Nef polyhedron to be correct.
+			// Passing an incorrect normal vector can cause a crash in the constrained delaunay triangulator
+      // See http://cgal-discuss.949826.n4.nabble.com/Nef3-Wrong-normal-vector-reported-causes-triangulator-crash-tt4660282.html
+			// CGAL::Vector_3<CGAL_Kernel3> nvec = plane.orthogonal_vector();
+			// K::Vector_3 normal(CGAL::to_double(nvec.x()), CGAL::to_double(nvec.y()), CGAL::to_double(nvec.z()));
 			std::vector<Polygon> triangles;
-			bool err = CGALUtils::tessellatePolygonWithHoles(polyholes, triangles, &normal);
+			bool err = CGALUtils::tessellatePolygonWithHoles(polyholes, triangles, NULL);
 			if (!err) {
 				BOOST_FOREACH(const Polygon &p, triangles) {
 					if (p.size() != 3) {