Index: Ringtoets/Piping/src/Ringtoets.Piping.IO/SurfaceLines/CharacteristicPointsCsvReader.cs
===================================================================
diff -u -r968645e02cdc2c21c899fa8099589c779138be54 -rcd17802422ec70791daa96e1f536bf505ecfe954
--- Ringtoets/Piping/src/Ringtoets.Piping.IO/SurfaceLines/CharacteristicPointsCsvReader.cs	(.../CharacteristicPointsCsvReader.cs)	(revision 968645e02cdc2c21c899fa8099589c779138be54)
+++ Ringtoets/Piping/src/Ringtoets.Piping.IO/SurfaceLines/CharacteristicPointsCsvReader.cs	(.../CharacteristicPointsCsvReader.cs)	(revision cd17802422ec70791daa96e1f536bf505ecfe954)
@@ -244,6 +244,8 @@
         {
             columnsInFile.Clear();
 
+            lineNumber = 1;
+
             string[] tokenizedHeader = TokenizeString(header.ToLowerInvariant().Replace(' ', '_'));
 
             if (!DetermineIdColumn(tokenizedHeader))