diff --git a/addons/google_calendar/google_calendar.py b/addons/google_calendar/google_calendar.py
index 32c030b6ea8..9a5a43c551c 100644
--- a/addons/google_calendar/google_calendar.py
+++ b/addons/google_calendar/google_calendar.py
@@ -946,7 +946,7 @@ class google_calendar(osv.AbstractModel):
         self.pool['res.users'].write(cr, SUPERUSER_ID, uid, vals, context=context)
 
     def get_minTime(self, cr, uid, context=None):
-        number_of_week = self.pool['ir.config_parameter'].get_param(cr, uid, 'calendar.week_synchro', default=13)
+        number_of_week = int(self.pool['ir.config_parameter'].get_param(cr, uid, 'calendar.week_synchro', default=13))
         return datetime.now() - timedelta(weeks=number_of_week)
 
     def get_need_synchro_attendee(self, cr, uid, context=None):