diff --git a/addons/event_sale/event_sale.py b/addons/event_sale/event_sale.py
index b7cb37571a4..0f2b1edbca0 100644
--- a/addons/event_sale/event_sale.py
+++ b/addons/event_sale/event_sale.py
@@ -19,6 +19,7 @@
 #
 ##############################################################################
 
+from openerp.addons.event.event import event_event as Event
 from openerp.osv import fields, osv
 from openerp.tools.translate import _
 
@@ -137,6 +138,11 @@ class event_event(osv.osv):
             pass
         return []
 
+    def _get_ticket_events(self, cr, uid, ids, context=None):
+        # `self` is the event.event.ticket model here! 
+        return list(set(ticket.event_id.id
+                            for ticket in self.browse(cr, uid, ids, context)))
+
     _columns = {
         'event_ticket_ids': fields.one2many('event.event.ticket', "event_id", "Event Ticket"),
         'seats_max': fields.function(_get_seats_max,
@@ -144,7 +150,15 @@ class event_event(osv.osv):
             help="The maximum registration level is equal to the sum of the maximum registration of event ticket." +
             "If you have too much registrations you are not able to confirm your event. (0 to ignore this rule )",
             type='integer',
-            readonly=True)
+            readonly=True),
+        'seats_available': fields.function(Event._get_seats, oldname='register_avail', string='Available Seats',
+                                           type='integer', multi='seats_reserved',
+                                           store={
+                                              'event.registration': (Event._get_events_from_registrations, ['state'], 10),
+                                              'event.event': (lambda self, cr, uid, ids, c = {}: ids,
+                                                              ['seats_max', 'registration_ids'], 20),
+                                              'event.event.ticket': (_get_ticket_events, ['seats_max'], 10),
+                                           }),
     }
     _defaults = {
         'event_ticket_ids': _get_tickets