diff --git a/usecase/device_details.go b/usecase/device_details.go
index 156dae2..4f2de14 100644
--- a/usecase/device_details.go
+++ b/usecase/device_details.go
@@ -554,6 +554,21 @@ func (u *deviceDetailsUseCase) UpdateDeviceDetails(id uuid.UUID, deviceDTO req.U
         }
         updates["tower_id"] = *deviceDTO.TowerID
     }
+
+    if deviceDTO.OLTID != nil {
+        // Validate OLT exists
+        oltExists, err := u.ValidateOLTExists(*deviceDTO.OLTID)
+        if err != nil {
+            return fmt.Errorf("failed to validate OLT: %w", err)
+        }
+        if !oltExists {
+            return fmt.Errorf("OLT with ID %s not found", deviceDTO.OLTID.String())
+        }
+
+        updates["olt_id"] = *deviceDTO.OLTID
+    }
+
+    log.Printf("Updating device %s with fields: %+v", id, updates)
     
     if len(updates) == 0 {
         return errors.New("no fields to update")