Index: Ringtoets/Revetment/src/Ringtoets.Revetment.Data/WaveConditionsInput.cs
===================================================================
diff -u -rea8531ddaa6352d92963b54023041fde69af5c49 -rb762914ea1a584bb69a286d389a8a6a83d171769
--- Ringtoets/Revetment/src/Ringtoets.Revetment.Data/WaveConditionsInput.cs	(.../WaveConditionsInput.cs)	(revision ea8531ddaa6352d92963b54023041fde69af5c49)
+++ Ringtoets/Revetment/src/Ringtoets.Revetment.Data/WaveConditionsInput.cs	(.../WaveConditionsInput.cs)	(revision b762914ea1a584bb69a286d389a8a6a83d171769)
@@ -217,15 +217,19 @@
 
         private static void ValidateRevetmentLevels(RoundedDouble lowerRevetmentLevelValue, RoundedDouble upperRevetmentLevelValue)
         {
-            if (lowerRevetmentLevelValue >= upperRevetmentLevelValue)
+            if (!double.IsNaN(lowerRevetmentLevelValue)
+                && !double.IsNaN(upperRevetmentLevelValue)
+                && lowerRevetmentLevelValue >= upperRevetmentLevelValue)
             {
                 throw new ArgumentOutOfRangeException(null, Resources.WaveConditionsInput_ValidateRevetmentLevels_Upper_revetment_level_must_be_above_lower_revetment_level);
             }
         }
 
         private static void ValidateCalculatorSeriesBoundaries(RoundedDouble lowerBoundary, RoundedDouble upperBoundary)
         {
-            if (lowerBoundary >= upperBoundary)
+            if (!double.IsNaN(lowerBoundary)
+                && !double.IsNaN(upperBoundary)
+                && lowerBoundary >= upperBoundary)
             {
                 throw new ArgumentOutOfRangeException(null, Resources.WaveConditionsInput_ValidateCalculatorSeriesBoundaries_Calculator_series_upperboundary_must_be_above_lowerboundary);
             }