diff --git a/openbsc/src/nat/bsc_nat_vty.c b/openbsc/src/nat/bsc_nat_vty.c
index 696a47c..c24f7e5 100644
--- a/openbsc/src/nat/bsc_nat_vty.c
+++ b/openbsc/src/nat/bsc_nat_vty.c
@@ -260,7 +260,7 @@
 
 DEFUN(cfg_nat_msc_ip,
       cfg_nat_msc_ip_cmd,
-      "msc ip IP",
+      "msc ip A.B.C.D",
       "Set the IP address of the MSC.")
 {
 	bsc_nat_set_msc_ip(_nat, argv[0]);