Index: Ringtoets/Common/src/Ringtoets.Common.IO/ReferenceLineImporter.cs
===================================================================
diff -u -rce31448a066c084f755439f3e7d453bfb042b291 -r7f759fbabca9c41e75d229269f1b21581b373b5f
--- Ringtoets/Common/src/Ringtoets.Common.IO/ReferenceLineImporter.cs	(.../ReferenceLineImporter.cs)	(revision ce31448a066c084f755439f3e7d453bfb042b291)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/ReferenceLineImporter.cs	(.../ReferenceLineImporter.cs)	(revision 7f759fbabca9c41e75d229269f1b21581b373b5f)
@@ -222,11 +222,7 @@
         {
             failureMechanism.ClearAllSections();
 
-            var observableFailureMechanism = failureMechanism as IObservable;
-            if (observableFailureMechanism != null)
-            {
-                changedObservables.Add(observableFailureMechanism);
-            }
+            changedObservables.Add(failureMechanism);
         }
 
         private void ClearHydraulicBoundaryOutput(IAssessmentSection assessmentSection)