Index: Ringtoets/Piping/src/Ringtoets.Piping.IO/Builders/SoilLayer2D.cs
===================================================================
diff -u -r49f905d3363336d44ef828259692644dcf5f9edc -r8ed108b83f575f6cb7dc1b89224606894a4bcb7a
--- Ringtoets/Piping/src/Ringtoets.Piping.IO/Builders/SoilLayer2D.cs	(.../SoilLayer2D.cs)	(revision 49f905d3363336d44ef828259692644dcf5f9edc)
+++ Ringtoets/Piping/src/Ringtoets.Piping.IO/Builders/SoilLayer2D.cs	(.../SoilLayer2D.cs)	(revision 8ed108b83f575f6cb7dc1b89224606894a4bcb7a)
@@ -160,7 +160,7 @@
                             BelowPhreaticLevel = BelowPhreaticLevel,
                             AbovePhreaticLevel = AbovePhreaticLevel,
                             DryUnitWeight = DryUnitWeight,
-                            MaterialName = MaterialName,
+                            MaterialName = MaterialName ?? string.Empty,
                             Color = SoilLayerColorConversionHelper.ColorFromNullableDouble(Color)
                         });
                     }