Index: Ringtoets/Integration/src/Ringtoets.Integration.Forms/Views/FailureMechanismContributionView.cs
===================================================================
diff -u -ra1bfcaebf502a6dca18c0256d692e8c94130327a -r5333bcb57fa6f4738d75699af5374e44ded4cdc2
--- Ringtoets/Integration/src/Ringtoets.Integration.Forms/Views/FailureMechanismContributionView.cs	(.../FailureMechanismContributionView.cs)	(revision a1bfcaebf502a6dca18c0256d692e8c94130327a)
+++ Ringtoets/Integration/src/Ringtoets.Integration.Forms/Views/FailureMechanismContributionView.cs	(.../FailureMechanismContributionView.cs)	(revision 5333bcb57fa6f4738d75699af5374e44ded4cdc2)
@@ -422,12 +422,10 @@
         private void ReturnPeriodNumericUpDown_Validating(object sender, CancelEventArgs e)
         {
             int returnPeriod = Convert.ToInt32(returnPeriodInput.Value);
-            if (returnPeriod == 0 || assessmentSection.FailureMechanismContribution.Norm.Equals(1.0/returnPeriod))
+            if (returnPeriod != 0 && 
+                !assessmentSection.FailureMechanismContribution.Norm.Equals(1.0/returnPeriod) && 
+                !normChangeHandler.ConfirmNormChange())
             {
-                return;
-            }
-            if (!normChangeHandler.ConfirmNormChange())
-            {
                 e.Cancel = true;
                 RevertReturnPeriodInputValue();
             }