diff --git a/lib/libc/gen/uexterr_format.c b/lib/libc/gen/uexterr_format.c
index 32b57ffb6e1a..86ba40234ae4 100644
--- a/lib/libc/gen/uexterr_format.c
+++ b/lib/libc/gen/uexterr_format.c
@@ -1,31 +1,35 @@
 /*-
  * SPDX-License-Identifier: BSD-2-Clause
  *
  * Copyright (c) 2025 The FreeBSD Foundation
  * All rights reserved.
  *
  * This software were developed by Konstantin Belousov <kib@FreeBSD.org>
  * under sponsorship from the FreeBSD Foundation.
  */
 
 #include <sys/types.h>
 #include <sys/exterrvar.h>
 #include <exterr.h>
 #include <stdio.h>
 #include <string.h>
 
 int
 __uexterr_format(const struct uexterror *ue, char *buf, size_t bufsz)
 {
 	if (bufsz > UEXTERROR_MAXLEN)
 		bufsz = UEXTERROR_MAXLEN;
 	if (ue->error == 0) {
 		strlcpy(buf, "No error", bufsz);
 		return (0);
 	}
-	snprintf(buf, bufsz,
-	    "errno %d category %u (src line %u) p1 %#jx p2 %#jx %s",
-	    ue->error, ue->cat, ue->src_line,
-	    (uintmax_t)ue->p1, (uintmax_t)ue->p2, ue->msg);
+	if (ue->msg[0] == '\0') {
+		snprintf(buf, bufsz,
+		    "errno %d category %u (src line %u) p1 %#jx p2 %#jx",
+		    ue->error, ue->cat, ue->src_line,
+		    (uintmax_t)ue->p1, (uintmax_t)ue->p2);
+	} else {
+		strlcpy(buf, ue->msg, bufsz);
+	}
 	return (0);
 }