diff --git a/python/adapters/ponsim_onu/ponsim_onu.py b/python/adapters/ponsim_onu/ponsim_onu.py
index e0592b4..0810376 100644
--- a/python/adapters/ponsim_onu/ponsim_onu.py
+++ b/python/adapters/ponsim_onu/ponsim_onu.py
@@ -199,7 +199,7 @@
         device.root = False
         device.vendor = 'ponsim'
         device.model = 'n/a'
-        device.serial_number = device.id
+        device.serial_number = device.serial_number
         device.mac_address = "AA:BB:CC:DD:E0:00"
         yield self.core_proxy.device_update(device)