Index: Ringtoets/GrassCoverErosionInwards/src/Ringtoets.GrassCoverErosionInwards.Data/GrassCoverErosionInwardsOutput.cs
===================================================================
diff -u -re7f6578ada32ed199d2b028ebb5eaeb691344592 -ra894ca6401da7f18b092ba73e48d1995e87d6d8f
--- Ringtoets/GrassCoverErosionInwards/src/Ringtoets.GrassCoverErosionInwards.Data/GrassCoverErosionInwardsOutput.cs	(.../GrassCoverErosionInwardsOutput.cs)	(revision e7f6578ada32ed199d2b028ebb5eaeb691344592)
+++ Ringtoets/GrassCoverErosionInwards/src/Ringtoets.GrassCoverErosionInwards.Data/GrassCoverErosionInwardsOutput.cs	(.../GrassCoverErosionInwardsOutput.cs)	(revision a894ca6401da7f18b092ba73e48d1995e87d6d8f)
@@ -71,9 +71,17 @@
             var clone = (GrassCoverErosionInwardsOutput) MemberwiseClone();
 
             clone.OvertoppingOutput = (OvertoppingOutput) OvertoppingOutput.Clone();
-            clone.DikeHeightOutput = (DikeHeightOutput) DikeHeightOutput.Clone();
-            clone.OvertoppingRateOutput = (OvertoppingRateOutput) OvertoppingRateOutput.Clone();
 
+            if (clone.DikeHeightOutput != null)
+            {
+                clone.DikeHeightOutput = (DikeHeightOutput) DikeHeightOutput.Clone();
+            }
+
+            if (clone.OvertoppingRateOutput != null)
+            {
+                clone.OvertoppingRateOutput = (OvertoppingRateOutput) OvertoppingRateOutput.Clone();
+            }
+
             return clone;
         }
     }