diff --git a/pms_api_rest/services/pms_folio_service.py b/pms_api_rest/services/pms_folio_service.py
index eb825c85a..e178db75f 100644
--- a/pms_api_rest/services/pms_folio_service.py
+++ b/pms_api_rest/services/pms_folio_service.py
@@ -427,7 +427,7 @@ class PmsFolioService(Component):
                             )[reservation.state],
                             children=reservation.children
                             if reservation.children
-                            else None,
+                            else 0,
                             readyForCheckin=reservation.ready_for_checkin,
                             allowedCheckout=reservation.allowed_checkout,
                             isSplitted=reservation.splitted,
diff --git a/pms_api_rest/services/pms_reservation_service.py b/pms_api_rest/services/pms_reservation_service.py
index bf5de4352..6230ca755 100644
--- a/pms_api_rest/services/pms_reservation_service.py
+++ b/pms_api_rest/services/pms_reservation_service.py
@@ -96,7 +96,7 @@ class PmsReservationService(Component):
                 stateDescription=dict(
                     reservation.fields_get(["state"])["state"]["selection"]
                 )[reservation.state],
-                children=reservation.children if reservation.children else None,
+                children=reservation.children if reservation.children else 0,
                 readyForCheckin=reservation.ready_for_checkin,
                 allowedCheckout=reservation.allowed_checkout,
                 isSplitted=reservation.splitted,