diff --git a/loanpy/src/loan/confirm_loan.py b/loanpy/src/loan/confirm_loan.py
index 3ef14d58ba0dfc340c6bf2883362da3fa3feea59..183a1c46a079f51cc610375fb13b27fc87e385cd 100755
--- a/loanpy/src/loan/confirm_loan.py
+++ b/loanpy/src/loan/confirm_loan.py
@@ -33,7 +33,8 @@ from .box_loan import (BOX, BOX_BORROWED, DESTINATION, F_LOAN, LENT, S_LENT, S_L
 def _set_lent_box(loan):
     """ Store the exact versions of borrowed items when it was delivered to the borrower. """
     references = set_references_to_current_version(loan.get_property(BOX).value)
-    loan.add_property(id=BOX.id, name=BOX_BORROWED.name, value=references,
+    borrowed_prop = db.get_entity_by_name(BOX_BORROWED.name, role="PROPERTY")
+    loan.add_property(id=borrowed_prop.id, value=references,
                       datatype=db.LIST(BOX.name) if isinstance(references, list) else BOX.name)
     loan.update()
 
diff --git a/loanpy/src/loan/manual_return.py b/loanpy/src/loan/manual_return.py
index b82e600111b95a8b83b921e1f54d4d0d40f23ae9..8b0facb70fdb67fb105e61a2de3846696cf6d0ea 100755
--- a/loanpy/src/loan/manual_return.py
+++ b/loanpy/src/loan/manual_return.py
@@ -37,7 +37,8 @@ def _set_returned_box(loan):
     This stores the version of the box that was returned by a borrower.
     """
     references = set_references_to_current_version(loan.get_property(BOX_BORROWED.name).value)
-    loan.add_property(id=BOX.id, name=BOX_RETURNED.name, value=references,
+    returned_prop = db.get_entity_by_name(BOX_RETURNED.name, role="PROPERTY")
+    loan.add_property(id=returned_prop.id, value=references,
                       datatype=db.LIST(BOX.name) if isinstance(references, list) else BOX.name)