Index: Ringtoets/Integration/src/Ringtoets.Integration.Forms/PropertyClasses/HydraulicBoundaryLocationDesignWaterLevelProperties.cs
===================================================================
diff -u -r7779966cdf2cc1cbaf00ce0643da3f47f34fa0af -rec29001a9e148ed508108e4fd64c2bc751a6c026
--- Ringtoets/Integration/src/Ringtoets.Integration.Forms/PropertyClasses/HydraulicBoundaryLocationDesignWaterLevelProperties.cs	(.../HydraulicBoundaryLocationDesignWaterLevelProperties.cs)	(revision 7779966cdf2cc1cbaf00ce0643da3f47f34fa0af)
+++ Ringtoets/Integration/src/Ringtoets.Integration.Forms/PropertyClasses/HydraulicBoundaryLocationDesignWaterLevelProperties.cs	(.../HydraulicBoundaryLocationDesignWaterLevelProperties.cs)	(revision ec29001a9e148ed508108e4fd64c2bc751a6c026)
@@ -19,6 +19,7 @@
 // Stichting Deltares and remain full property of Stichting Deltares at all times.
 // All rights reserved.
 
+using System;
 using System.Globalization;
 using Core.Common.Base.Geometry;
 using Core.Common.Gui.Attributes;
@@ -76,7 +77,7 @@
         {
             get
             {
-                return double.IsNaN(data.DesignWaterLevel) ? "" : data.DesignWaterLevel.ToString("F2", CultureInfo.InvariantCulture);
+                return double.IsNaN(data.DesignWaterLevel) ? string.Empty : data.DesignWaterLevel.ToString("F2", CultureInfo.InvariantCulture);
             }
         }
     }