diff --git a/models/event.py b/models/event.py
index 9e0293c..1c40d09 100644
--- a/models/event.py
+++ b/models/event.py
@@ -31,7 +31,9 @@ class Event(models.Model):
     def _compute_duration(self):
         for event in self:
             if event.duration is True:
+                fmt = '%Y-%m-%d'
                 t1 = fields.Datetime.from_string(event.date_end)
                 t2 = fields.Datetime.from_string(event.date_start)
                 d1 = datetime.strptime(t1, fmt)
                 d2 = datetime.strptime(t2, fmt)
+                daysDiff = str((d2-d1).day)