diff --git a/mctest.py b/mctest.py
index 6c3dd08..b8b2416 100755
--- a/mctest.py
+++ b/mctest.py
@@ -82,7 +82,7 @@ def sender(mgroup):
 if args.ttl:
     mttl = int(args.ttl)
 if args.port:
-    mport = args.port
+    mport = int(args.port)
 
 if args.send:
     message = args.send