Index: Ringtoets/Common/src/Ringtoets.Common.Forms/Factories/RingtoetsMapDataFeaturesFactory.cs
===================================================================
diff -u -r9b2bb9a809f4b42bd06b910dde1f6eb8e546356f -r876c8ac8eedb2905f2dc10edebacf2428146d271
--- Ringtoets/Common/src/Ringtoets.Common.Forms/Factories/RingtoetsMapDataFeaturesFactory.cs	(.../RingtoetsMapDataFeaturesFactory.cs)	(revision 9b2bb9a809f4b42bd06b910dde1f6eb8e546356f)
+++ Ringtoets/Common/src/Ringtoets.Common.Forms/Factories/RingtoetsMapDataFeaturesFactory.cs	(.../RingtoetsMapDataFeaturesFactory.cs)	(revision 876c8ac8eedb2905f2dc10edebacf2428146d271)
@@ -100,11 +100,16 @@
         /// </summary>
         /// <param name="hydraulicBoundaryDatabase">The <see cref="HydraulicBoundaryDatabase"/>
         /// to create the location features for.</param>
-        /// <returns>A collection of features or an empty collection when <paramref name="hydraulicBoundaryDatabase"/> 
-        /// is <c>null</c>.</returns>
+        /// <returns>A collection of features.</returns>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="hydraulicBoundaryDatabase"/> is <c>null</c>.</exception>
         public static IEnumerable<MapFeature> CreateHydraulicBoundaryDatabaseFeatures(HydraulicBoundaryDatabase hydraulicBoundaryDatabase)
         {
-            return CreateHydraulicBoundaryLocationFeatures(hydraulicBoundaryDatabase?.Locations.ToArray() ?? new HydraulicBoundaryLocation[0],
+            if (hydraulicBoundaryDatabase == null)
+            {
+                throw new ArgumentNullException(nameof(hydraulicBoundaryDatabase));
+            }
+
+            return CreateHydraulicBoundaryLocationFeatures(hydraulicBoundaryDatabase.Locations.ToArray(),
                                                            Resources.DesignWaterLevel_DisplayName,
                                                            Resources.MetaData_WaveHeight);
         }
Index: Ringtoets/Common/test/Ringtoets.Common.Forms.Test/Factories/RingtoetsMapDataFeaturesFactoryTest.cs
===================================================================
diff -u -r9b2bb9a809f4b42bd06b910dde1f6eb8e546356f -r876c8ac8eedb2905f2dc10edebacf2428146d271
--- Ringtoets/Common/test/Ringtoets.Common.Forms.Test/Factories/RingtoetsMapDataFeaturesFactoryTest.cs	(.../RingtoetsMapDataFeaturesFactoryTest.cs)	(revision 9b2bb9a809f4b42bd06b910dde1f6eb8e546356f)
+++ Ringtoets/Common/test/Ringtoets.Common.Forms.Test/Factories/RingtoetsMapDataFeaturesFactoryTest.cs	(.../RingtoetsMapDataFeaturesFactoryTest.cs)	(revision 876c8ac8eedb2905f2dc10edebacf2428146d271)
@@ -114,13 +114,14 @@
         }
 
         [Test]
-        public void CreateHydraulicBoundaryDatabaseFeatures_HydraulicBoundaryDatabaseNull_ReturnsEmptyFeaturesCollection()
+        public void CreateHydraulicBoundaryDatabaseFeatures_HydraulicBoundaryDatabaseNull_ThrowArgumentNullException()
         {
             // Call
-            IEnumerable<MapFeature> features = RingtoetsMapDataFeaturesFactory.CreateHydraulicBoundaryDatabaseFeatures(null);
+            TestDelegate test = () => RingtoetsMapDataFeaturesFactory.CreateHydraulicBoundaryDatabaseFeatures(null);
 
             // Assert
-            CollectionAssert.IsEmpty(features);
+            var exception = Assert.Throws<ArgumentNullException>(test);
+            Assert.AreEqual("hydraulicBoundaryDatabase", exception.ParamName);
         }
 
         [Test]