Index: Ringtoets/Common/src/Ringtoets.Common.IO/Readers/CalculationConfigurationReaderHelper.cs
===================================================================
diff -u -r7a466d4ccb9d859b47f565b400808eb6933b18f0 -r90d46f7d803d51c0a68ee35569cf3c918e5387fd
--- Ringtoets/Common/src/Ringtoets.Common.IO/Readers/CalculationConfigurationReaderHelper.cs	(.../CalculationConfigurationReaderHelper.cs)	(revision 7a466d4ccb9d859b47f565b400808eb6933b18f0)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/Readers/CalculationConfigurationReaderHelper.cs	(.../CalculationConfigurationReaderHelper.cs)	(revision 90d46f7d803d51c0a68ee35569cf3c918e5387fd)
@@ -41,7 +41,7 @@
         /// <returns>The value of the element, or <c>null</c> when the <paramref name="parentElement"/>
         /// does not have descendant elements of <paramref name="descendantElementName"/>.</returns>
         /// <exception cref="ArgumentNullException">Thrown when any parameter is <c>null</c>.</exception>
-        public static double? GetDoubleValueFromDescendantElement(XElement parentElement, string descendantElementName)
+        public static double? GetDoubleValueFromDescendantElement(this XElement parentElement, string descendantElementName)
         {
             if (parentElement == null)
             {