diff --git a/Kill.c b/Kill.c
index f5c5821..63442a6 100644
--- a/Kill.c
+++ b/Kill.c
@@ -29,7 +29,7 @@
 #include	"md_u.h"
 #include	"md_p.h"
 
-int Kill(char *dev, int force, int quiet, int noexcl)
+int Kill(char *dev, struct supertype *st, int force, int quiet, int noexcl)
 {
 	/*
 	 * Nothing fancy about Kill.  It just zeroes out a superblock
@@ -37,11 +37,10 @@ int Kill(char *dev, int force, int quiet, int noexcl)
 	 */
 
 	int fd, rv = 0;
-	struct supertype *st;
 
 	if (force)
 		noexcl = 1;
-	fd = open(dev, O_RDWR|(force ? 0 : O_EXCL));
+	fd = open(dev, O_RDWR|(noexcl ? 0 : O_EXCL));
 	if (fd < 0) {
 		if (!quiet)
 			fprintf(stderr, Name ": Couldn't open %s for write - not zeroing\n",
@@ -49,12 +48,13 @@ int Kill(char *dev, int force, int quiet, int noexcl)
 		close(fd);
 		return 1;
 	}
-	st = guess_super(fd);
+	if (st == NULL)
+		st = guess_super(fd);
 	if (st == NULL) {
 		if (!quiet)
 			fprintf(stderr, Name ": Unrecognised md component device - %s\n", dev);
 		close(fd);
-		return 1;
+		return 2;
 	}
 	rv = st->ss->load_super(st, fd, dev);
 	if (force && rv >= 2)
diff --git a/mdadm.c b/mdadm.c
index 3dc8be9..74a39a8 100644
--- a/mdadm.c
+++ b/mdadm.c
@@ -1361,7 +1361,16 @@ int main(int argc, char *argv[])
 						     export, test, homehost);
 					continue;
 				case 'K': /* Zero superblock */
-					rv |= Kill(dv->devname, force, quiet,0);
+					if (ss)
+						rv |= Kill(dv->devname, ss, force, quiet,0);
+					else {
+						int q = quiet;
+						do {
+							rv |= Kill(dv->devname, NULL, force, q, 0);
+							q = 1;
+						} while ((rv & 2) == 0);
+						rv &= ~2;
+					}
 					continue;
 				case 'Q':
 					rv |= Query(dv->devname); continue;
diff --git a/mdadm.h b/mdadm.h
index 261cdb7..c7f864b 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -756,7 +756,7 @@ extern int Monitor(mddev_dev_t devlist,
 		   int period, int daemonise, int scan, int oneshot,
 		   int dosyslog, int test, char *pidfile, int increments);
 
-extern int Kill(char *dev, int force, int quiet, int noexcl);
+extern int Kill(char *dev, struct supertype *st, int force, int quiet, int noexcl);
 extern int Wait(char *dev);
 extern int WaitClean(char *dev, int sock, int verbose);
 
diff --git a/super0.c b/super0.c
index 15b3ca2..0485a3a 100644
--- a/super0.c
+++ b/super0.c
@@ -725,8 +725,8 @@ static int write_init_super0(struct supertype *st)
 			continue;
 		if (di->fd == -1)
 			continue;
-		Kill(di->devname, 0, 1, 1);
-		Kill(di->devname, 0, 1, 1);
+		while (Kill(di->devname, NULL, 0, 1, 1) == 0)
+			;
 
 		sb->disks[di->disk.number].state &= ~(1<<MD_DISK_FAULTY);
 
diff --git a/super1.c b/super1.c
index 5a2df0e..2c992a4 100644
--- a/super1.c
+++ b/super1.c
@@ -1016,8 +1016,8 @@ static int write_init_super1(struct supertype *st)
 		if (di->fd < 0)
 			continue;
 
-		Kill(di->devname, 0, 1, 1);
-		Kill(di->devname, 0, 1, 1);
+		while (Kill(di->devname, NULL, 0, 1, 1) == 0)
+			;
 
 		sb->dev_number = __cpu_to_le32(di->disk.number);
 		if (di->disk.state & (1<<MD_DISK_WRITEMOSTLY))