diff --git a/python/radio.py b/python/radio.py
index 1614842..08930c5 100644
--- a/python/radio.py
+++ b/python/radio.py
@@ -82,7 +82,7 @@ class modes_radio (gr.top_block, pubsub):
       
     #Choose source
     group.add_option("-s","--source", type="string", default="uhd",
-                      help="Choose source: uhd, osmocom, <filename>, or <ip:port>")
+                      help="Choose source: uhd, osmocom, <filename>, or <ip:port> [default=%default]")
 
     #UHD/Osmocom args
     group.add_option("-R", "--subdev", type="string",