Index: Ringtoets/Revetment/test/Ringtoets.Revetment.IO.Test/Configurations/WaveConditionsCalculationConfigurationWriterTest.cs
===================================================================
diff -u -r5fd714a68d3fb4f70136fc41c2af6a40f0156f19 -r3a60f4df420a7669a047880a924bf4a0ff67c265
--- Ringtoets/Revetment/test/Ringtoets.Revetment.IO.Test/Configurations/WaveConditionsCalculationConfigurationWriterTest.cs	(.../WaveConditionsCalculationConfigurationWriterTest.cs)	(revision 5fd714a68d3fb4f70136fc41c2af6a40f0156f19)
+++ Ringtoets/Revetment/test/Ringtoets.Revetment.IO.Test/Configurations/WaveConditionsCalculationConfigurationWriterTest.cs	(.../WaveConditionsCalculationConfigurationWriterTest.cs)	(revision 3a60f4df420a7669a047880a924bf4a0ff67c265)
@@ -19,8 +19,10 @@
 // Stichting Deltares and remain full property of Stichting Deltares at all times.
 // All rights reserved.
 
+using System;
 using System.IO;
 using Core.Common.Base.Data;
+using Core.Common.IO.Exceptions;
 using Core.Common.TestUtil;
 using NUnit.Framework;
 using Ringtoets.Common.IO.Configurations;
@@ -122,6 +124,28 @@
             }
         }
 
+        [Test]
+        public void Write_InvalidStepSize_ThrowsCriticalFileWriteException()
+        {
+            // Setup
+            var configuration = new WaveConditionsCalculationConfiguration("fail")
+            {
+                StepSize = (ConfigurationWaveConditionsInputStepSize?)9000
+            };
+
+            var writer = new WaveConditionsCalculationConfigurationWriter("valid");
+
+            // Call
+            TestDelegate call = () => writer.Write(new[]
+            {
+                configuration
+            });
+
+            // Assert
+            var exception = Assert.Throws<CriticalFileWriteException>(call);
+            Assert.IsInstanceOf<NotSupportedException>(exception.InnerException);
+        }
+
         protected override WaveConditionsCalculationConfigurationWriter CreateWriterInstance(string filePath)
         {
             return new WaveConditionsCalculationConfigurationWriter(filePath);