diff --git a/usr/local/www/diag_nanobsd.php b/usr/local/www/diag_nanobsd.php
index e57ad5c258..3b311bbdf7 100755
--- a/usr/local/www/diag_nanobsd.php
+++ b/usr/local/www/diag_nanobsd.php
@@ -85,18 +85,38 @@ if($_POST['bootslice']) {
 EOF;
 	for ($i = 0; $i < ob_get_level(); $i++) { ob_end_flush(); }
 	ob_implicit_flush(1);
-	exec("gpart set -a active -i {$SLICE} {$BOOT_DRIVE}");
-	exec("/usr/sbin/boot0cfg -s {$SLICE} -v /dev/{$BOOT_DRIVE}");
-	exec("/bin/mkdir /tmp/{$GLABEL_SLICE}");
-	exec("/sbin/mount /dev/ufs/{$GLABEL_SLICE} /tmp/{$GLABEL_SLICE}");
-	exec("/bin/cp /etc/fstab /tmp/{$GLABEL_SLICE}/etc/fstab");
-	$status = exec("sed -i \"\" \"s/pfsense{$OLD_UFS_ID}/pfsense{$UFS_ID}/g\" /tmp/{$GLABEL_SLICE}/etc/fstab");
+	if(strstr($_POST['bootslice'], "s1")) {
+		$ASLICE="2";
+		$AOLDSLICE="1";
+		$ATOFLASH="{$BOOT_DRIVE}s{$SLICE}";
+		$ACOMPLETE_PATH="{$BOOT_DRIVE}s{$SLICE}a";
+		$AGLABEL_SLICE="pfsense1";
+		$AUFS_ID="1";
+		$AOLD_UFS_ID="0";
+		$ABOOTFLASH="{$BOOT_DRIVE}s{$OLDSLICE}";
+	} else {
+		$ASLICE="1";
+		$AOLDSLICE="2";
+		$ATOFLASH="{$BOOT_DRIVE}s{$SLICE}";
+		$ACOMPLETE_PATH="{$BOOT_DRIVE}s{$SLICE}a";
+		$AGLABEL_SLICE="pfsense0";
+		$AUFS_ID="0";
+		$AOLD_UFS_ID="1";
+		$ABOOTFLASH="{$BOOT_DRIVE}s{$OLDSLICE}";
+	}
+	exec("gpart set -a active -i {$ASLICE} {$ABOOT_DRIVE}");
+	exec("/usr/sbin/boot0cfg -s {$ASLICE} -v /dev/{$ABOOT_DRIVE}");
+	exec("/bin/mkdir /tmp/{$AGLABEL_SLICE}");
+	exec("/sbin/fsck_ufs -y /dev/{$ACOMPLETE_PATH}");
+	exec("/sbin/mount /dev/ufs/{$AGLABEL_SLICE} /tmp/{$AGLABEL_SLICE}");
+	exec("/bin/cp /etc/fstab /tmp/{$AGLABEL_SLICE}/etc/fstab");
+	$status = exec("sed -i \"\" \"s/pfsense{$AOLD_UFS_ID}/pfsense{$AUFS_ID}/g\" /tmp/{$AGLABEL_SLICE}/etc/fstab");
 	if($status) {
 		file_notice("UpgradeFailure","Something went wrong when trying to update the fstab entry.  Aborting upgrade.");
-		exec("/sbin/umount /tmp/{$GLABEL_SLICE}");
+		exec("/sbin/umount /tmp/{$AGLABEL_SLICE}");
 	}
-	exec("/sbin/umount /tmp/{$GLABEL_SLICE}");
-	$savemsg = "The boot slice has been set to {$BOOT_DRIVE} {$SLICE}";
+	exec("/sbin/umount /tmp/{$AGLABEL_SLICE}");
+	$savemsg = "The boot slice has been set to {$ABOOT_DRIVE} {$ASLICE}";
 }
 
 if($_POST['destslice']) {