From 557967c36ce4d80412405fb2ac20b599186689ba Mon Sep 17 00:00:00 2001
From: nicm <nicm@openbsd.org>
Date: Mon, 7 Sep 2026 10:15:25 +0000
Subject: [PATCH] Do not silently make a session monitor if the target is
 unknown, GitHub issue 5575 from zzchun12826 at gmail dot com.

---
 monitor.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/monitor.c b/monitor.c
index ff0c6e5ed..596e137a7 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor.c,v 1.7 2026/07/27 19:15:58 nicm Exp $ */
+/* $OpenBSD: monitor.c,v 1.8 2026/09/07 10:15:25 nicm Exp $ */
 
 /*
  * Copyright (c) 2026 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -614,8 +614,10 @@ monitor_parse(const char *value, char **name, enum monitor_type *type, int *id,
 		*type = MONITOR_ALL_WINDOWS;
 	else if (sscanf(what, "@%d", id) == 1 && *id >= 0)
 		*type = MONITOR_WINDOW;
-	else
+	else if (*what == '\0')
 		*type = MONITOR_SESSION;
+	else
+		goto fail;
 	*name = xstrdup(copy);
 	*format = xstrdup(split);