diff --git a/src/main/java/no/nibio/vips/model/oatfloweringmodel/OatFloweringModel.java b/src/main/java/no/nibio/vips/model/oatfloweringmodel/OatFloweringModel.java
index 2948f9b3209f84e452cd090d9aaf941cecb6074e..4991014b6e1fee9ae4c3d12d7f93d8effa63de77 100755
--- a/src/main/java/no/nibio/vips/model/oatfloweringmodel/OatFloweringModel.java
+++ b/src/main/java/no/nibio/vips/model/oatfloweringmodel/OatFloweringModel.java
@@ -122,6 +122,7 @@ public class OatFloweringModel extends I18nImpl implements Model{
     private Result initResult(WeatherObservation obs)
     {
         Calendar cal = Calendar.getInstance();
+        cal.setFirstDayOfWeek(Calendar.MONDAY);
         Result result = new ResultImpl();
         result.setValidTimeStart(obs.getTimeMeasured());
         
diff --git a/src/test/java/OatFloweringModelTest.java b/src/test/java/OatFloweringModelTest.java
index c45033ccfafc0b43d23768ea150f8c8ed2d850e3..71e745703a09f253511692b7439055b7a20ab74e 100755
--- a/src/test/java/OatFloweringModelTest.java
+++ b/src/test/java/OatFloweringModelTest.java
@@ -119,7 +119,7 @@ public class OatFloweringModelTest {
                 System.out.println("Result: [" + result.getValidTimeStart() + "]" + result.getAllValues());
             }*/
             
-            assertEquals("27", weekResult);
+            assertEquals("26", weekResult);
             assertEquals("60", zReached);
             
         }