Index: Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Plugin/HeightStructuresPlugin.cs
===================================================================
diff -u -rcf60de33a75f1d729639a4ba7f30e3b319f9ed6d -re402805257d7185512020535bd0df9cd01a7734e
--- Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Plugin/HeightStructuresPlugin.cs	(.../HeightStructuresPlugin.cs)	(revision cf60de33a75f1d729639a4ba7f30e3b319f9ed6d)
+++ Ringtoets/HeightStructures/src/Ringtoets.HeightStructures.Plugin/HeightStructuresPlugin.cs	(.../HeightStructuresPlugin.cs)	(revision e402805257d7185512020535bd0df9cd01a7734e)
@@ -575,14 +575,17 @@
                           .Build();
         }
 
-        private StrictContextMenuItem CreateUpdateStructureItem(StructuresCalculation<HeightStructuresInput>[] calculations)
+        private StrictContextMenuItem CreateUpdateStructureItem(
+            IEnumerable<StructuresCalculation<HeightStructuresInput>> calculations)
         {
             var contextMenuEnabled = true;
             string toolTipMessage = RingtoetsCommonFormsResources.StructuresPlugin_CreateUpdateStructureItem_Update_all_calculations_with_Structure_Tooltip;
-            IList<StructuresCalculation<HeightStructuresInput>> calculationsToUpdate = calculations
-                .Where(c => c.InputParameters.Structure != null && !c.InputParameters.IsStructureInputSynchronized)
-                .ToList();
 
+            StructuresCalculation<HeightStructuresInput>[] calculationsToUpdate = calculations
+                .Where(calc => calc.InputParameters.Structure != null
+                               && !calc.InputParameters.IsStructureInputSynchronized)
+                .ToArray();
+
             if (!calculationsToUpdate.Any())
             {
                 contextMenuEnabled = false;