diff --git a/libraries/utils.robot b/libraries/utils.robot
index 2cfe4ea..7ee2f79 100644
--- a/libraries/utils.robot
+++ b/libraries/utils.robot
@@ -286,7 +286,7 @@
         ...    ${olt_device_id}
         ${List_ONU_Serial}    Create List
         Set Suite Variable    ${List_ONU_Serial}
-        Build ONU SN List    ${List_ONU_Serial}
+        Build ONU SN List    ${List_ONU_Serial}    ${olt_serial_number}
         Log    ${List_ONU_Serial}
         Run Keyword    Wait Until Keyword Succeeds    ${timeout}    5s    Validate ONU Flows
         ...    ${List_ONU_Serial}    ${onu_flows}