diff --git a/cpp/README.md b/cpp/README.md
index 078021d8760ba9a511184b159e152c73fbd5863a..759e10bfe1ff8e261aca06e9c8e6e780c227b14d 100644
--- a/cpp/README.md
+++ b/cpp/README.md
@@ -49,7 +49,7 @@ Build client and server:
 ```sh
 $ make
 ```
-Run the server:
+Run the server, which will listen on port 50051:
 ```sh
 $ ./greeter_server
 ```