--- libaitcli/src/aitcli.c	2025/12/25 20:20:11	1.21.2.8
+++ libaitcli/src/aitcli.c	2025/12/25 20:24:32	1.21.2.9
@@ -3,7 +3,7 @@
 *  by Michael Pounov <misho@openbsd-bg.org>
 *
 * $Author: misho $
-* $Id: aitcli.c,v 1.21.2.8 2025/12/25 20:20:11 misho Exp $
+* $Id: aitcli.c,v 1.21.2.9 2025/12/25 20:24:32 misho Exp $
 *
 **************************************************************************
 The ELWIX and AITNET software is distributed under the following
@@ -758,9 +758,14 @@ cli_Printf(linebuffer_t * __restrict cli_buffer, char 
 {
 	va_list lst;
 	FILE *f;
+	int fd;
 
 	if (fmt) {
-		f = fdopen(dup(cli_buffer->line_out), "a");
+		if ((fd = dup(cli_buffer->line_out)) == -1) {
+			LOGERR;
+			return;
+		}
+		f = fdopen(fd, "a");
 		if (!f) {
 			LOGERR;
 			return;