Index: Ringtoets/GrassCoverErosionInwards/src/Ringtoets.GrassCoverErosionInwards.Plugin/GrassCoverErosionInwardsPlugin.cs
===================================================================
diff -u -rf70611f9af51a6ffc8cb4d8d28d1ea806104937b -rb1712af5a19e0e5fa7037e14f61d9d9496483bfa
--- Ringtoets/GrassCoverErosionInwards/src/Ringtoets.GrassCoverErosionInwards.Plugin/GrassCoverErosionInwardsPlugin.cs	(.../GrassCoverErosionInwardsPlugin.cs)	(revision f70611f9af51a6ffc8cb4d8d28d1ea806104937b)
+++ Ringtoets/GrassCoverErosionInwards/src/Ringtoets.GrassCoverErosionInwards.Plugin/GrassCoverErosionInwardsPlugin.cs	(.../GrassCoverErosionInwardsPlugin.cs)	(revision b1712af5a19e0e5fa7037e14f61d9d9496483bfa)
@@ -528,11 +528,12 @@
             var parentGroupContext = (GrassCoverErosionInwardsCalculationGroupContext) parentNodeData;
 
             parentGroupContext.WrappedData.Children.Remove(context.WrappedData);
+            var grassCoverErosionInwardsCalculations = context.FailureMechanism.Calculations.Cast<GrassCoverErosionInwardsCalculation>().ToArray();
             foreach (var calculation in context.WrappedData.GetCalculations().Cast<GrassCoverErosionInwardsCalculation>())
             {
                 GrassCoverErosionInwardsHelper.Delete(context.FailureMechanism.SectionResults,
                                                       calculation,
-                                                      context.FailureMechanism.Calculations.Cast<GrassCoverErosionInwardsCalculation>());
+                                                      grassCoverErosionInwardsCalculations);
             }
             parentGroupContext.NotifyObservers();
         }