diff --git a/lib/chkname.c b/lib/chkname.c
index 98f791706..bee2e6bd7 100644
--- a/lib/chkname.c
+++ b/lib/chkname.c
@@ -2,7 +2,7 @@
 // SPDX-FileCopyrightText: 1996-2000, Marek Michałkiewicz
 // SPDX-FileCopyrightText: 2001-2005, Tomasz Kłoczko
 // SPDX-FileCopyrightText: 2005-2008, Nicolas François
-// SPDX-FileCopyrightText: 2023-2024, Alejandro Colomar <alx@kernel.org>
+// SPDX-FileCopyrightText: 2023-2025, Alejandro Colomar <alx@kernel.org>
 // SPDX-License-Identifier: BSD-3-Clause
 
 
@@ -27,8 +27,6 @@
 #include <limits.h>
 #include <stdbool.h>
 #include <stddef.h>
-#include <stdint.h>
-#include <sys/param.h>
 #include <unistd.h>
 
 #include "defines.h"
@@ -36,6 +34,11 @@
 #include "string/strcmp/streq.h"
 
 
+#ifndef  LOGIN_NAME_MAX
+# define LOGIN_NAME_MAX  256
+#endif
+
+
 int allow_bad_names = false;
 
 
@@ -44,12 +47,11 @@ login_name_max_size(void)
 {
 	long  conf;
 
-	errno = 0;
 	conf = sysconf(_SC_LOGIN_NAME_MAX);
-	if (conf == -1 && errno != 0)
+	if (conf == -1)
 		return LOGIN_NAME_MAX;
 
-	return MIN(conf, PTRDIFF_MAX);
+	return conf;
 }