Index: Ringtoets/Piping/src/Ringtoets.Piping.IO/SurfaceLines/CharacteristicPointsCsvReader.cs
===================================================================
diff -u -r6afbb616ce84cccaf56617d60c5cd821b00daab0 -r9cdd70c8d4ba76d93b72ef8c1b7df138fa73b0e4
--- Ringtoets/Piping/src/Ringtoets.Piping.IO/SurfaceLines/CharacteristicPointsCsvReader.cs	(.../CharacteristicPointsCsvReader.cs)	(revision 6afbb616ce84cccaf56617d60c5cd821b00daab0)
+++ Ringtoets/Piping/src/Ringtoets.Piping.IO/SurfaceLines/CharacteristicPointsCsvReader.cs	(.../CharacteristicPointsCsvReader.cs)	(revision 9cdd70c8d4ba76d93b72ef8c1b7df138fa73b0e4)
@@ -196,7 +196,7 @@
         /// required format or the file is empty.</exception>
         private void ValidateHeader(TextReader reader)
         {
-            var currentLine = 1;
+            const int currentLine = 1;
             string header = ReadLineAndHandleIOExceptions(reader, currentLine);
             if (header != null)
             {