Index: Ringtoets/Common/test/Ringtoets.Common.Service.Test/DesignWaterLevelCalculationActivityTest.cs
===================================================================
diff -u -r24e18b63dccdb718dac61c69cc55289553cbaa47 -r122edb15a01ee908bf7774f862258b6606522c68
--- Ringtoets/Common/test/Ringtoets.Common.Service.Test/DesignWaterLevelCalculationActivityTest.cs	(.../DesignWaterLevelCalculationActivityTest.cs)	(revision 24e18b63dccdb718dac61c69cc55289553cbaa47)
+++ Ringtoets/Common/test/Ringtoets.Common.Service.Test/DesignWaterLevelCalculationActivityTest.cs	(.../DesignWaterLevelCalculationActivityTest.cs)	(revision 122edb15a01ee908bf7774f862258b6606522c68)
@@ -360,11 +360,11 @@
             };
 
             string validFilePath = Path.Combine(testDataPath, validFile);
-            const int returnPeriod = 300;
+            const double norm = 1.0/300;
             var activity = new DesignWaterLevelCalculationActivity(hydraulicBoundaryLocation,
                                                                    validFilePath,
                                                                    string.Empty,
-                                                                   returnPeriod,
+                                                                   norm,
                                                                    calculationMessageProviderMock);
 
             using (new HydraRingCalculatorFactoryConfig())
@@ -411,12 +411,11 @@
 
             string validFilePath = Path.Combine(testDataPath, validFile);
 
-            var returnPeriod = 30;
-
+            const double norm = 1.0 / 30;
             var activity = new DesignWaterLevelCalculationActivity(hydraulicBoundaryLocation,
                                                                    validFilePath,
                                                                    string.Empty,
-                                                                   returnPeriod,
+                                                                   norm,
                                                                    calculationMessageProviderMock);
 
             using (new HydraRingCalculatorFactoryConfig())