diff --git a/src/python/oftest/testutils.py b/src/python/oftest/testutils.py
index e87b7a0..d92f180 100644
--- a/src/python/oftest/testutils.py
+++ b/src/python/oftest/testutils.py
@@ -1596,7 +1596,10 @@
             # Found a matching message
             break
 
-    test.assertTrue(msg == None, "Did not expect a packet-in message on port %d" % in_port)
+    if in_port == None:
+        test.assertTrue(msg == None, "Did not expect a packet-in message on any port")
+    else:
+        test.assertTrue(msg == None, "Did not expect a packet-in message on port %d" % in_port)
 
 def openflow_ports(num=None):
     """