diff --git a/USAGE.txt b/USAGE.txt
index c73d7e1908..25f32c551f 100644
--- a/USAGE.txt
+++ b/USAGE.txt
@@ -27,6 +27,7 @@ Options:
     Prints version.
 
   --listen=<proto>://[addr][:port]
+  --listen=socks://[[user]:[pass]@][addr][:port]
 
     Listens at addr:port with protocol <proto>.