--- np2/x11/cmserial.c	2011/01/15 16:48:39	1.5
+++ np2/x11/cmserial.c	2012/01/23 04:23:10	1.8
@@ -1,5 +1,3 @@
-/*	$Id: cmserial.c,v 1.5 2011/01/15 16:48:39 monaka Exp $	*/
-
 /*
  * Copyright (c) 2004 NONAKA Kimihiro
  * All rights reserved.
@@ -94,6 +92,10 @@ serialgetstat(COMMNG self)
 	int rv;
 
 	rv = ioctl(serial->hdl, TIOCMGET, &status);
+	if (rv < 0) {
+		VERBOSE(("serialgetstat: ioctl: %s", strerror(errno)));
+		return 0x20;
+	}
 	if (!(status & TIOCM_DSR)) {
 		VERBOSE(("serialgetstat: DSR is disable"));
 		return 0x20;