diff --git a/sys/arm64/arm64/ofw_machdep.c b/sys/arm64/arm64/ofw_machdep.c
index 3941c1d35617..61aa4c1a1208 100644
--- a/sys/arm64/arm64/ofw_machdep.c
+++ b/sys/arm64/arm64/ofw_machdep.c
@@ -1,58 +1,64 @@
 /*-
  * Copyright (c) 2015 Ian Lepore <ian@freebsd.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/bus.h>
 
 #include <machine/bus.h>
 
 #include <dev/ofw/openfirm.h>
 #include <dev/ofw/ofw_subr.h>
 
 extern struct bus_space memmap_bus;
 
 int
 OF_decode_addr(phandle_t dev, int regno, bus_space_tag_t *tag,
     bus_space_handle_t *handle, bus_size_t *sz)
 {
 	bus_addr_t addr;
 	bus_size_t size;
-	int err;
+	phandle_t parent;
+	int err, flags;
 
 	err = ofw_reg_to_paddr(dev, regno, &addr, &size, NULL);
 	if (err != 0)
 		return (err);
 
 	*tag = &memmap_bus;
 
 	if (sz != NULL)
 		*sz = size;
 
-	return (bus_space_map(*tag, addr, size, 0, handle));
+	flags = 0;
+	parent = OF_parent(dev);
+	if (parent > 0 && OF_hasprop(parent, "nonposted-mmio"))
+		flags |= BUS_SPACE_MAP_NONPOSTED;
+
+	return (bus_space_map(*tag, addr, size, flags, handle));
 }