diff --git a/SAS/TMSS/backend/src/tmss/tmssapp/models/specification.py b/SAS/TMSS/backend/src/tmss/tmssapp/models/specification.py
index 7e3b5624af75cc7dd4e4a6787e7d7b9e8ff6304a..39bbacd4f7efc4ec6bc8c2005d0bfa23d7734f58 100644
--- a/SAS/TMSS/backend/src/tmss/tmssapp/models/specification.py
+++ b/SAS/TMSS/backend/src/tmss/tmssapp/models/specification.py
@@ -522,7 +522,7 @@ class SchedulingUnitBlueprint(RefreshFromDbInvalidatesCachedPropertiesMixin, Tem
                 raise TMSSException('The scheduling constraints of SchedulingUnitBlueprint pk=%s status=%s cannot be updated since it is not in defined or schedulable state.' % (self.pk, self.status))
 
         # update the original constraints value for comparison on next save
-        self.__original_scheduling_constraints_doc = dict(self.scheduling_constraints_doc)
+        self.__original_scheduling_constraints_doc = self.scheduling_constraints_doc
         self.__original_scheduling_constraints_template_id = self.scheduling_constraints_template_id
 
         super().save(force_insert, force_update, using, update_fields)