Index: usr.sbin/bsdinstall/scripts/zfsboot
===================================================================
--- usr.sbin/bsdinstall/scripts/zfsboot	(revision 273422)
+++ usr.sbin/bsdinstall/scripts/zfsboot	(working copy)
@@ -197,6 +197,7 @@
 GPART_CREATE='gpart create -s %s "%s"'
 GPART_DESTROY_F='gpart destroy -F "%s"'
 GPART_SET_ACTIVE='gpart set -a active -i %s "%s"'
+GPART_SET_DISK_ACTIVE='gpart set -a active "%s"'
 GRAID_DELETE='graid delete "%s"'
 LN_SF='ln -sf "%s" "%s"'
 MKDIR_P='mkdir -p "%s"'
@@ -870,6 +871,16 @@
 		             zfs$index freebsd-zfs $disk || return $FAILURE
 		f_eval_catch -d $funcname zpool "$ZPOOL_LABELCLEAR_F" \
 		                /dev/$disk$targetpart
+
+		#
+		# 5. Set the pMBR active if booted via BIOS
+		#
+		bootmethod=$(sysctl -n machdep.bootmethod)
+		f_dprintf "machdep.bootmethod=[%s]" "$bootmethod"
+		if [ "$bootmethod" = "BIOS" ]; then
+			f_eval_catch $funcname gpart \
+				"$GPART_SET_DISK_ACTIVE" $disk ||
+				return $FAILURE
 		;;
 
 	MBR) f_dprintf "$funcname: Creating MBR layout..."