diff --git a/nh_eobs/models/nh_clinical_patient_monitoring_exception.py b/nh_eobs/models/nh_clinical_patient_monitoring_exception.py
index c25f13b0..f75cc73b 100644
--- a/nh_eobs/models/nh_clinical_patient_monitoring_exception.py
+++ b/nh_eobs/models/nh_clinical_patient_monitoring_exception.py
@@ -33,6 +33,7 @@ def start(self, activity_id):
     def complete(self, activity_id):
         return super(PatientMonitoringException, self).complete(activity_id)
 
+    @api.model
     def cancel(self, activity_id):
         return super(PatientMonitoringException, self).cancel(activity_id)