diff --git a/src/core/quiesce.c b/src/core/quiesce.c
new file mode 100644
index 00000000..5d2a919d
--- /dev/null
+++ b/src/core/quiesce.c
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2017 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+/**
+ * @file
+ *
+ * Quiesce system
+ *
+ */
+
+#include <ipxe/quiesce.h>
+
+/** Quiesce system */
+void quiesce ( void ) {
+	struct quiescer *quiescer;
+
+	/* Call all quiescers */
+	for_each_table_entry ( quiescer, QUIESCERS ) {
+		quiescer->quiesce();
+	}
+}
+
+/** Unquiesce system */
+void unquiesce ( void ) {
+	struct quiescer *quiescer;
+
+	/* Call all quiescers */
+	for_each_table_entry ( quiescer, QUIESCERS ) {
+		quiescer->unquiesce();
+	}
+}
diff --git a/src/core/sanboot.c b/src/core/sanboot.c
index 1fd63490..cabc4843 100644
--- a/src/core/sanboot.c
+++ b/src/core/sanboot.c
@@ -41,6 +41,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #include <ipxe/iso9660.h>
 #include <ipxe/dhcp.h>
 #include <ipxe/settings.h>
+#include <ipxe/quiesce.h>
 #include <ipxe/sanboot.h>
 
 /**
@@ -365,6 +366,9 @@ int sandev_reopen ( struct san_device *sandev ) {
 	struct san_path *sanpath;
 	int rc;
 
+	/* Unquiesce system */
+	unquiesce();
+
 	/* Close any outstanding command and restart interfaces */
 	sandev_restart ( sandev, -ECONNRESET );
 	assert ( sandev->active == NULL );
@@ -503,6 +507,9 @@ sandev_command ( struct san_device *sandev,
 	/* Sanity check */
 	assert ( ! timer_running ( &sandev->timer ) );
 
+	/* Unquiesce system */
+	unquiesce();
+
 	/* (Re)try command */
 	do {
 
@@ -654,6 +661,14 @@ int sandev_write ( struct san_device *sandev, uint64_t lba,
 	if ( ( rc = sandev_rw ( sandev, lba, count, buffer, block_write ) ) != 0 )
 		return rc;
 
+	/* Quiesce system.  This is a heuristic designed to ensure
+	 * that the system is quiesced before Windows starts up, since
+	 * a Windows SAN boot will typically write a status flag to
+	 * the disk as its last action before transferring control to
+	 * the native drivers.
+	 */
+	quiesce();
+
 	return 0;
 }
 
diff --git a/src/include/ipxe/quiesce.h b/src/include/ipxe/quiesce.h
new file mode 100644
index 00000000..00b530b8
--- /dev/null
+++ b/src/include/ipxe/quiesce.h
@@ -0,0 +1,31 @@
+#ifndef _IPXE_QUIESCE_H
+#define _IPXE_QUIESCE_H
+
+/** @file
+ *
+ * Quiesce system
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <ipxe/tables.h>
+
+/** A quiescer */
+struct quiescer {
+	/** Quiesce system */
+	void ( * quiesce ) ( void );
+	/** Unquiesce system */
+	void ( * unquiesce ) ( void );
+};
+
+/** Quiescer table */
+#define QUIESCERS __table ( struct quiescer, "quiescers" )
+
+/** Declare a quiescer */
+#define __quiescer __table_entry ( QUIESCERS, 01 )
+
+extern void quiesce ( void );
+extern void unquiesce ( void );
+
+#endif /* _IPXE_QUIESCE_H */