diff --git a/maintenance.py b/maintenance.py
index 1e96229..df968d9 100644
--- a/maintenance.py
+++ b/maintenance.py
@@ -55,7 +55,10 @@ class MaintenanceService(Workflow, ModelSQL, ModelView):
     propietary = fields.Many2One(
         'party.party', 'Propietary', required=True, states=_states
     )
-    contract_origin = fields.Many2One('optical_equipment.contract', "Contract")
+    contract_origin = fields.Many2One(
+        'optical_equipment.contract', "Contract",
+        domain=[('party', '=', Eval('propietary'))]
+                                      )
     # contract_origin = fields.Reference(
     #    'Contract Base',
     #    selection='get_origin_contract')