diff --git a/addons/event_sale/models/sale_order.py b/addons/event_sale/models/sale_order.py
index fd589e41e8a..60b84a2eaf0 100644
--- a/addons/event_sale/models/sale_order.py
+++ b/addons/event_sale/models/sale_order.py
@@ -29,6 +29,10 @@ class SaleOrder(models.Model):
                     ._for_xml_id('event_sale.action_sale_order_event_registration')
         return res
 
+    def action_cancel(self):
+        self.order_line._cancel_associated_registrations()
+        return super(SaleOrder, self).action_cancel()
+
     def action_view_attendee_list(self):
         action = self.env["ir.actions.actions"]._for_xml_id("event.event_registration_action_tree")
         action['domain'] = [('sale_order_id', 'in', self.ids)]
@@ -128,6 +132,9 @@ class SaleOrderLine(models.Model):
         self._unlink_associated_registrations()
         return super(SaleOrderLine, self).unlink()
 
+    def _cancel_associated_registrations(self):
+        self.env['event.registration'].search([('sale_order_line_id', 'in', self.ids)]).action_cancel()
+
     def _unlink_associated_registrations(self):
         self.env['event.registration'].search([('sale_order_line_id', 'in', self.ids)]).unlink()
 
diff --git a/addons/event_sale/tests/test_event_sale.py b/addons/event_sale/tests/test_event_sale.py
index 65a777ef6b0..b4d5bd9e23e 100644
--- a/addons/event_sale/tests/test_event_sale.py
+++ b/addons/event_sale/tests/test_event_sale.py
@@ -270,3 +270,13 @@ class TestEventSale(TestEventSaleCommon):
         self.assertEqual(event.seats_expected, 1)
         self.sale_order.order_line.unlink()
         self.assertEqual(event.seats_expected, 0)
+
+    @users('user_salesman')
+    def test_cancel_so(self):
+        """ This test ensures that when canceling a sale order, if the latter is linked to an event registration,
+        the number of expected seats will be correctly updated """
+        event = self.env['event.event'].browse(self.event_0.ids)
+        self.register_person.action_make_registration()
+        self.assertEqual(event.seats_expected, 1)
+        self.sale_order.action_cancel()
+        self.assertEqual(event.seats_expected, 0)