diff --git a/gio/gsocketlistener.c b/gio/gsocketlistener.c
index a2c879d9c..7bc4d1a44 100644
--- a/gio/gsocketlistener.c
+++ b/gio/gsocketlistener.c
@@ -965,7 +965,9 @@ g_socket_listener_accept_finish (GSocketListener  *listener,
  * @listener: a #GSocketListener
  * @listen_backlog: an integer
  *
- * Sets the listen backlog on the sockets in the listener.
+ * Sets the listen backlog on the sockets in the listener. This must be called
+ * before adding any sockets, addresses or ports to the #GSocketListener (for
+ * example, by calling g_socket_listener_add_inet_port()) to be effective.
  *
  * See g_socket_set_listen_backlog() for details
  *