diff --git a/sys/dev/scsipi/cd.c b/sys/dev/scsipi/cd.c
index f5e68c836ccb..eb432d3a3986 100644
--- a/sys/dev/scsipi/cd.c
+++ b/sys/dev/scsipi/cd.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: cd.c,v 1.298 2010/03/11 04:00:36 mrg Exp $	*/
+/*	$NetBSD: cd.c,v 1.299 2010/03/22 16:49:41 martin Exp $	*/
 
 /*-
  * Copyright (c) 1998, 2001, 2003, 2004, 2005, 2008 The NetBSD Foundation,
@@ -50,7 +50,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: cd.c,v 1.298 2010/03/11 04:00:36 mrg Exp $");
+__KERNEL_RCSID(0, "$NetBSD: cd.c,v 1.299 2010/03/22 16:49:41 martin Exp $");
 
 #include "rnd.h"
 
@@ -1270,6 +1270,7 @@ cdioctl(dev_t dev, u_long cmd, void *addr, int flag, struct lwp *l)
 		case ODIOCEJECT:
 		case DIOCEJECT:
 		case DIOCCACHESYNC:
+		case DIOCTUR:
 		case SCIOCIDENTIFY:
 		case OSCIOCIDENTIFY:
 		case SCIOCCOMMAND:
@@ -1397,6 +1398,15 @@ cdioctl(dev_t dev, u_long cmd, void *addr, int flag, struct lwp *l)
 		return error;
 #endif
 
+	case DIOCTUR: {
+		/* test unit ready */
+		error = scsipi_test_unit_ready(cd->sc_periph, XS_CTL_SILENT);
+		*((int*)addr) = (error == 0);
+		if (error == ENODEV || error == EIO || error == 0)
+			return 0;			
+		return error;
+	}
+
 	case CDIOCPLAYTRACKS: {
 		/* PLAY_MSF command */
 		struct ioc_play_track *args = addr;
diff --git a/sys/sys/dkio.h b/sys/sys/dkio.h
index 517df3222105..a6c3a72528fc 100644
--- a/sys/sys/dkio.h
+++ b/sys/sys/dkio.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: dkio.h,v 1.15 2009/12/22 18:55:25 pooka Exp $	*/
+/*	$NetBSD: dkio.h,v 1.16 2010/03/22 16:49:41 martin Exp $	*/
 
 /*
  * Copyright (c) 1987, 1988, 1993
@@ -105,4 +105,7 @@
 		/* get disk-info dictionary */
 #define	DIOCGDISKINFO	_IOR('d', 127, struct plistref)
 
+
+#define	DIOCTUR		_IOR('d', 128, int)	/* test unit ready */
+
 #endif /* _SYS_DKIO_H_ */