diff --git a/tools/gtp-link.c b/tools/gtp-link.c
index 8367c6e..d342f2b 100644
--- a/tools/gtp-link.c
+++ b/tools/gtp-link.c
@@ -46,7 +46,8 @@
 	int ret, sgsn_mode = 0;
 
 	if (argc < 3) {
-		printf("Usage: %s <add|del> <device>\n", argv[0]);
+		printf("Usage: %s add <device> [--sgsn]\n", argv[0]);
+		printf("       %s del <device>\n", argv[0]);
 		exit(EXIT_FAILURE);
 	}