diff --git a/golem_season/models/golem_season.py b/golem_season/models/golem_season.py
index f2d7aed..9b1dc6e 100644
--- a/golem_season/models/golem_season.py
+++ b/golem_season/models/golem_season.py
@@ -54,11 +54,10 @@ class GolemSeason(models.Model):
         """ Check if end date if after start date and if there is no conflict
         with existing periods """
         for season in self:
-            if season.date_start:
-                if not season.date_end:
+            if season.date_start or season.date_end:
+                if season.date_start and not season.date_end:
                     raise models.ValidationError(_('The date end is required'))
-            if season.date_end:
-                if not season.date_start:
+                elif season.date_end and not season.date_start:
                     raise models.ValidationError(_('The date start is required'))
 
             if season.date_start > season.date_end:
diff --git a/golem_season/tests/test_golem_season.py b/golem_season/tests/test_golem_season.py
index 6d60925..0080c71 100644
--- a/golem_season/tests/test_golem_season.py
+++ b/golem_season/tests/test_golem_season.py
@@ -55,13 +55,18 @@ class TestGolemSeason(TransactionCase):
                                       'date_start': '2009-11-01',
                                       'date_end': '2011-12-31'})
 
+
+        self.assertTrue({'name': 'date_end and date_start is empty',
+                         'date_start': False,
+                         'date_end': False})
+
         with self.assertRaises(ValidationError):
-            self.season_model.create({'name': 'date_end is nul',
+            self.season_model.create({'name': 'date_end is empty',
                                       'date_start': '2009-11-01',
                                       'date_end': False})
 
         with self.assertRaises(ValidationError):
-            self.season_model.create({'name': 'date_start is nul',
+            self.season_model.create({'name': 'date_start is empty',
                                       'date_start' : False,
                                       'date_end': '2009-11-01'})