Index: Ringtoets/Common/test/Ringtoets.Common.Service.Test/IllustrationPoints/IllustrationPointConverterTest.cs
===================================================================
diff -u -ra6da010d4a68dbf5b4571ea39850ee92f62d2496 -r2bda1fe026b3f2c9bf6f4d0254e3292bbd887f78
--- Ringtoets/Common/test/Ringtoets.Common.Service.Test/IllustrationPoints/IllustrationPointConverterTest.cs	(.../IllustrationPointConverterTest.cs)	(revision a6da010d4a68dbf5b4571ea39850ee92f62d2496)
+++ Ringtoets/Common/test/Ringtoets.Common.Service.Test/IllustrationPoints/IllustrationPointConverterTest.cs	(.../IllustrationPointConverterTest.cs)	(revision 2bda1fe026b3f2c9bf6f4d0254e3292bbd887f78)
@@ -52,11 +52,8 @@
         {
             // Setup
             var random = new Random(21);
-            var hydraIllustrationPointResult = new HydraIllustrationPointResult
-            {
-                Description = "HydraIllustrationPointResult",
-                Value = random.NextDouble()
-            };
+            var hydraIllustrationPointResult = new HydraIllustrationPointResult("HydraIllustrationPointResult",
+                                                                                random.NextDouble());
             var hydraRealizedStochast = new HydraRealizedStochast
             {
                 Alpha = random.NextDouble(),
Index: Ringtoets/Common/test/Ringtoets.Common.Service.Test/IllustrationPoints/IllustrationPointResultConverterTest.cs
===================================================================
diff -u -r0fd23ff8e68b5f0d18d344d104bc68216cb49b51 -r2bda1fe026b3f2c9bf6f4d0254e3292bbd887f78
--- Ringtoets/Common/test/Ringtoets.Common.Service.Test/IllustrationPoints/IllustrationPointResultConverterTest.cs	(.../IllustrationPointResultConverterTest.cs)	(revision 0fd23ff8e68b5f0d18d344d104bc68216cb49b51)
+++ Ringtoets/Common/test/Ringtoets.Common.Service.Test/IllustrationPoints/IllustrationPointResultConverterTest.cs	(.../IllustrationPointResultConverterTest.cs)	(revision 2bda1fe026b3f2c9bf6f4d0254e3292bbd887f78)
@@ -47,11 +47,8 @@
         {
             // Setup
             var random = new Random(21);
-            var hydraIllustrationPointResult = new HydraIllustrationPointResult
-            {
-                Description = "Description",
-                Value = random.NextDouble()
-            };
+            var hydraIllustrationPointResult = new HydraIllustrationPointResult("Description",
+                                                                                random.NextDouble());
 
             // Call
             IllustrationPointResult illustrationPointResult = IllustrationPointResultConverter.CreateIllustrationPointResult(hydraIllustrationPointResult);
Index: Ringtoets/Common/test/Ringtoets.Common.Service.Test/IllustrationPoints/WindDirectionClosingSituationIllustrationPointConverterTest.cs
===================================================================
diff -u -ra6da010d4a68dbf5b4571ea39850ee92f62d2496 -r2bda1fe026b3f2c9bf6f4d0254e3292bbd887f78
--- Ringtoets/Common/test/Ringtoets.Common.Service.Test/IllustrationPoints/WindDirectionClosingSituationIllustrationPointConverterTest.cs	(.../WindDirectionClosingSituationIllustrationPointConverterTest.cs)	(revision a6da010d4a68dbf5b4571ea39850ee92f62d2496)
+++ Ringtoets/Common/test/Ringtoets.Common.Service.Test/IllustrationPoints/WindDirectionClosingSituationIllustrationPointConverterTest.cs	(.../WindDirectionClosingSituationIllustrationPointConverterTest.cs)	(revision 2bda1fe026b3f2c9bf6f4d0254e3292bbd887f78)
@@ -85,11 +85,8 @@
 
             var windDirectionClosingSituation = new HydraWindDirectionClosingSituation(hydraWindDirection, closingScenario);
 
-            var hydraIllustrationPointResult = new HydraIllustrationPointResult
-            {
-                Description = "HydraIllustrationPointResult",
-                Value = random.NextDouble()
-            };
+            var hydraIllustrationPointResult = new HydraIllustrationPointResult("HydraIllustrationPointResult",
+                                                                                random.NextDouble());
             var hydraRealizedStochast = new HydraRealizedStochast
             {
                 Alpha = random.NextDouble(),
@@ -109,7 +106,8 @@
 
             // Call
             WindDirectionClosingSituationIllustrationPoint combination =
-                WindDirectionClosingSituationIllustrationPointConverter.CreateWindDirectionClosingScenarioIllustrationPoint(windDirectionClosingSituation, subMechanismIllustrationPoint);
+                WindDirectionClosingSituationIllustrationPointConverter.CreateWindDirectionClosingScenarioIllustrationPoint(
+                    windDirectionClosingSituation, subMechanismIllustrationPoint);
 
             // Assert
             WindDirection windDirection = combination.WindDirection;
Index: Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Data/Output/IllustrationPoints/IllustrationPointResult.cs
===================================================================
diff -u -r0fd23ff8e68b5f0d18d344d104bc68216cb49b51 -r2bda1fe026b3f2c9bf6f4d0254e3292bbd887f78
--- Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Data/Output/IllustrationPoints/IllustrationPointResult.cs	(.../IllustrationPointResult.cs)	(revision 0fd23ff8e68b5f0d18d344d104bc68216cb49b51)
+++ Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Data/Output/IllustrationPoints/IllustrationPointResult.cs	(.../IllustrationPointResult.cs)	(revision 2bda1fe026b3f2c9bf6f4d0254e3292bbd887f78)
@@ -19,6 +19,8 @@
 // Stichting Deltares and remain full property of Stichting Deltares at all times.
 // All rights reserved.
 
+using System;
+
 namespace Ringtoets.HydraRing.Calculation.Data.Output.IllustrationPoints
 {
     /// <summary>
@@ -27,13 +29,31 @@
     public class IllustrationPointResult
     {
         /// <summary>
-        /// Gets or sets the description.
+        /// Creates a new instance of <see cref="IllustrationPointResult"/>.
         /// </summary>
-        public string Description { get; set; }
+        /// <param name="description">The description.</param>
+        /// <param name="value">The output of the sub mechanism illustration point.</param>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="description"/> 
+        /// is <c>null</c>.</exception>
+        public IllustrationPointResult(string description, double value)
+        {
+            if (description == null)
+            {
+                throw new ArgumentNullException(nameof(description));
+            }
 
+            Description = description;
+            Value = value;
+        }
+
         /// <summary>
-        /// Gets or sets the value.
+        /// Gets the description.
         /// </summary>
-        public double Value { get; set; } = double.NaN;
+        public string Description { get; }
+
+        /// <summary>
+        /// Gets the value.
+        /// </summary>
+        public double Value { get; }
     }
 }
\ No newline at end of file
Index: Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Parsers/IllustrationPoints/IllustrationPointsParser.cs
===================================================================
diff -u -ra6da010d4a68dbf5b4571ea39850ee92f62d2496 -r2bda1fe026b3f2c9bf6f4d0254e3292bbd887f78
--- Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Parsers/IllustrationPoints/IllustrationPointsParser.cs	(.../IllustrationPointsParser.cs)	(revision a6da010d4a68dbf5b4571ea39850ee92f62d2496)
+++ Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Parsers/IllustrationPoints/IllustrationPointsParser.cs	(.../IllustrationPointsParser.cs)	(revision 2bda1fe026b3f2c9bf6f4d0254e3292bbd887f78)
@@ -262,11 +262,7 @@
                     subMechanismResults[key] = new List<IllustrationPointResult>();
                 }
 
-                subMechanismResults[key].Add(new IllustrationPointResult
-                {
-                    Description = description,
-                    Value = value
-                });
+                subMechanismResults[key].Add(new IllustrationPointResult(description, value));
             }
         }
 
Index: Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/Data/Output/IllustrationPoints/IllustrationPointResultTest.cs
===================================================================
diff -u -r0fd23ff8e68b5f0d18d344d104bc68216cb49b51 -r2bda1fe026b3f2c9bf6f4d0254e3292bbd887f78
--- Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/Data/Output/IllustrationPoints/IllustrationPointResultTest.cs	(.../IllustrationPointResultTest.cs)	(revision 0fd23ff8e68b5f0d18d344d104bc68216cb49b51)
+++ Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/Data/Output/IllustrationPoints/IllustrationPointResultTest.cs	(.../IllustrationPointResultTest.cs)	(revision 2bda1fe026b3f2c9bf6f4d0254e3292bbd887f78)
@@ -19,6 +19,7 @@
 // Stichting Deltares and remain full property of Stichting Deltares at all times.
 // All rights reserved.
 
+using System;
 using NUnit.Framework;
 using Ringtoets.HydraRing.Calculation.Data.Output.IllustrationPoints;
 
@@ -28,14 +29,29 @@
     public class IllustrationPointResultTest
     {
         [Test]
+        public void Constructor_DescriptionNull_ThrowsArgumentNullException()
+        {
+            // Call
+            TestDelegate call = () => new IllustrationPointResult(null, 0);
+
+            // Assert
+            string paramName = Assert.Throws<ArgumentNullException>(call).ParamName;
+            Assert.AreEqual("description", paramName);
+        }
+
+        [Test]
         public void Constructor_Always_ReturnsNewInstance()
         {
+            // Setup
+            const string description = "some description";
+            const double value = 123;
+
             // Call
-            var result = new IllustrationPointResult();
+            var result = new IllustrationPointResult(description, value);
 
             // Assert
-            Assert.IsNull(result.Description);
-            Assert.IsNaN(result.Value);
+            Assert.AreEqual(description, result.Description);
+            Assert.AreEqual(value, result.Value);
         }
     }
 }
\ No newline at end of file