diff --git a/src/main.c b/src/main.c
index 164c17d..2d5c4a9 100644
--- a/src/main.c
+++ b/src/main.c
@@ -28,7 +28,8 @@
 /* usage */
 static int _usage(void)
 {
-	fputs("Usage: " PROGNAME " [-R]\n", stderr);
+	fputs("Usage: " PROGNAME " [-R]\n"
+"  -R   Register the service with the Session\n", stderr);
 	return 1;
 }