diff --git a/DiffractionGratings/grating3D.geo b/DiffractionGratings/grating3D.geo
index 9ac0bb2f2a1ba98edee1960eb703de730a12a559..a2671b5fc7a4824dfdf75e2af3d4cfca029aa881 100644
--- a/DiffractionGratings/grating3D.geo
+++ b/DiffractionGratings/grating3D.geo
@@ -292,5 +292,8 @@ Mesh.ElementOrder = og;
 If (og==2)
   Mesh.HighOrderOptimize = 1;
 EndIf
+If (og==1)
+  Mesh.Optimize = 1;
+EndIf
 
-// Solver.SocketName=Sprintf("socktest%g",socketid);
\ No newline at end of file
+// Solver.SocketName=Sprintf("socktest%g",socketid);