diff --git a/ip/xfrm_monitor.c b/ip/xfrm_monitor.c
index 79453e41..8aa6f495 100644
--- a/ip/xfrm_monitor.c
+++ b/ip/xfrm_monitor.c
@@ -374,7 +374,7 @@ int do_xfrm_monitor(int argc, char **argv)
 			groups = 0;
 		} else if (matches(*argv, "help") == 0) {
 			usage();
-		} else {
+		} else if (strcmp(*argv, "all")) {
 			fprintf(stderr, "Argument \"%s\" is unknown, try \"ip xfrm monitor help\".\n", *argv);
 			exit(-1);
 		}