diff --git a/src/python/oftest/dataplane.py b/src/python/oftest/dataplane.py
index bdbfea7..29b7fad 100644
--- a/src/python/oftest/dataplane.py
+++ b/src/python/oftest/dataplane.py
@@ -50,6 +50,7 @@
         """
         Set up a port monitor object
         @param interface_name The name of the physical interface like eth1
+        @param port_number The port number associated with this port
         @param parent The controlling dataplane object; for pkt wait CV
         @param max_pkts Maximum number of pkts to keep in queue
         """