diff --git a/migrate/chaindb4to5.js b/migrate/chaindb4to6.js
similarity index 54%
rename from migrate/chaindb4to5.js
rename to migrate/chaindb4to6.js
index b9eb1f0b..0e9e8b36 100644
--- a/migrate/chaindb4to5.js
+++ b/migrate/chaindb4to6.js
@@ -8,8 +8,9 @@ const {resolve} = require('path');
 
 assert(process.argv.length > 2, 'Please pass in a database path.');
 
-// migration -
-// chaindb: leveldb to flat files
+// Changes:
+// 1. Moves blocks and undo blocks from leveldb to flat files.
+// 2. Removes tx and addr indexes from chaindb.
 
 const db = bdb.create({
   location: process.argv[2],
@@ -25,29 +26,33 @@ const blockStore = new FileBlockStore({
   location: location
 });
 
-async function updateVersion() {
-  const ver = await checkVersion();
+async function getVersion() {
+  const data = await db.get(layout.V.encode());
+  assert(data, 'No version.');
 
-  console.log('Updating version to %d.', ver + 1);
+  return data.readUInt32LE(5, true);
+}
+
+async function updateVersion(version) {
+  await checkVersion(version - 1);
+
+  console.log('Updating version to %d.', version);
 
   const buf = Buffer.allocUnsafe(5 + 4);
   buf.write('chain', 0, 'ascii');
-  buf.writeUInt32LE(5, 5, true);
+  buf.writeUInt32LE(version, 5, true);
 
   const parent = db.batch();
   parent.put(layout.V.encode(), buf);
   await parent.write();
 }
 
-async function checkVersion() {
+async function checkVersion(version) {
   console.log('Checking version.');
 
-  const data = await db.get(layout.V.encode());
-  assert(data, 'No version.');
+  const ver = await getVersion();
 
-  const ver = data.readUInt32LE(5, true);
-
-  if (ver !== 4)
+  if (ver !== version)
     throw Error(`DB is version ${ver}.`);
 
   return ver;
@@ -113,26 +118,85 @@ async function migrateBlocks() {
   await parent.write();
 }
 
+async function removeKey(name, key) {
+  const iter = db.iterator({
+    gte: key.min(),
+    lte: key.max(),
+    reverse: true,
+    keys: true
+  });
+
+  let batch = db.batch();
+  let total = 0;
+
+  while (await iter.next()) {
+    const {key} = iter;
+    batch.del(key);
+
+    if (++total % 10000 === 0) {
+      console.log('Cleaned up %d %s index records.', total, name);
+      await batch.write();
+      batch = db.batch();
+    }
+  }
+  await batch.write();
+
+  console.log('Cleaned up %d %s index records.', total, name);
+}
+
+async function migrateIndexes() {
+  const t = bdb.key('t', ['hash256']);
+  const T = bdb.key('T', ['hash', 'hash256']);
+  const C = bdb.key('C', ['hash', 'hash256', 'uint32']);
+
+  await removeKey('hash -> tx', t);
+  await removeKey('addr -> tx', T);
+  await removeKey('addr -> coin', C);
+}
+
 /*
  * Execute
  */
 
 (async () => {
   await db.open();
-  await blockStore.ensure();
-  await blockStore.open();
 
   console.log('Opened %s.', process.argv[2]);
 
-  await checkVersion();
-  await migrateBlocks();
-  await migrateUndoBlocks();
-  await updateVersion();
+  const version = await getVersion();
+  let compact = false;
+
+  switch (version) {
+    case 4:
+      // Upgrade from version 4 to 5.
+      await checkVersion(4);
+      await blockStore.ensure();
+      await blockStore.open();
+      await migrateBlocks();
+      await migrateUndoBlocks();
+      await updateVersion(5);
+      await blockStore.close();
+      compact = true;
+    case 5:
+      // Upgrade from version 5 to 6.
+      await checkVersion(5);
+      await migrateIndexes();
+      await updateVersion(6);
+      compact = true;
+      break;
+    case 6:
+      console.log('Already upgraded.');
+      break;
+    default:
+      console.log(`DB version is ${version}.`);
+  }
+
+  if (compact) {
+    console.log('Compacting database');
+    await db.compactRange();
+  }
 
-  console.log('Compacting database');
-  await db.compactRange();
   await db.close();
-  await blockStore.close();
 })().then(() => {
   console.log('Migration complete.');
   process.exit(0);
diff --git a/migrate/chaindb5to6.js b/migrate/chaindb5to6.js
deleted file mode 100644
index 8a85b607..00000000
--- a/migrate/chaindb5to6.js
+++ /dev/null
@@ -1,105 +0,0 @@
-'use strict';
-
-const assert = require('assert');
-const bdb = require('bdb');
-const layout = require('../lib/blockchain/layout');
-
-// changes:
-// removes tx, addr indexes i.e layout.t, layout.T, layout.C
-
-assert(process.argv.length > 2, 'Please pass in a database path.');
-
-const db = bdb.create({
-  location: process.argv[2],
-  memory: false,
-  compression: true,
-  cacheSize: 32 << 20,
-  createIfMissing: false
-});
-
-async function updateVersion() {
-  const ver = await checkVersion();
-
-  console.log('Updating version to %d.', ver + 1);
-
-  const buf = Buffer.allocUnsafe(5 + 4);
-  buf.write('chain', 0, 'ascii');
-  buf.writeUInt32LE(6, 5, true);
-
-  const parent = db.batch();
-  parent.put(layout.V.encode(), buf);
-  await parent.write();
-}
-
-async function checkVersion() {
-  console.log('Checking version.');
-
-  const data = await db.get(layout.V.encode());
-  assert(data, 'No version.');
-
-  const ver = data.readUInt32LE(5, true);
-
-  if (ver !== 5)
-    throw Error(`DB is version ${ver}.`);
-
-  return ver;
-}
-
-async function removeKey(name, key) {
-  const iter = db.iterator({
-    gte: key.min(),
-    lte: key.max(),
-    reverse: true,
-    keys: true
-  });
-
-  let batch = db.batch();
-  let total = 0;
-
-  while (await iter.next()) {
-    const {key} = iter;
-    batch.del(key);
-
-    if (++total % 10000 === 0) {
-      console.log('Cleaned up %d %s index records.', total, name);
-      await batch.write();
-      batch = db.batch();
-    }
-  }
-  await batch.write();
-
-  console.log('Cleaned up %d %s index records.', total, name);
-}
-
-async function migrateIndexes() {
-  const t = bdb.key('t', ['hash256']);
-  const T = bdb.key('T', ['hash', 'hash256']);
-  const C = bdb.key('C', ['hash', 'hash256', 'uint32']);
-
-  await removeKey('hash -> tx', t);
-  await removeKey('addr -> tx', T);
-  await removeKey('addr -> coin', C);
-}
-
-/*
- * Execute
- */
-
-(async () => {
-  await db.open();
-
-  console.log('Opened %s.', process.argv[2]);
-
-  await checkVersion();
-  await migrateIndexes();
-  await updateVersion();
-
-  await db.compactRange();
-  await db.close();
-})().then(() => {
-  console.log('Migration complete.');
-  process.exit(0);
-}).catch((err) => {
-  console.error(err.stack);
-  process.exit(1);
-});
diff --git a/migrate/latest b/migrate/latest
index dd0e1c13..b4ebd981 100755
--- a/migrate/latest
+++ b/migrate/latest
@@ -3,7 +3,8 @@
 'use strict';
 
 const cp = require('child_process');
-const res = require('path').resolve;
+const fs = require('bfile');
+const {resolve} = require('path');
 const {argv} = process;
 
 if (argv.length < 3) {
@@ -31,8 +32,16 @@ function exec(file, ...args) {
 const node = argv[0];
 const prefix = argv[2];
 
-exec(node, res(__dirname, 'chaindb3to4.js'), res(prefix, 'chain'));
-exec(node, res(__dirname, 'chaindb3to4.js'), res(prefix, 'spvchain'));
-exec(node, res(__dirname, 'chaindb4to5.js'), res(prefix, 'chain'));
-exec(node, res(__dirname, 'chaindb5to6.js'), res(prefix, 'chain'));
-exec(node, res(__dirname, 'walletdb6to7.js'), res(prefix, 'wallet'));
+const chain = resolve(prefix, 'chain');
+const spvchain = resolve(prefix, 'spvchain');
+
+(async () => {
+  if (await fs.exists(chain))
+    exec(node, resolve(__dirname, 'chaindb4to6.js'), chain);
+
+  if (await fs.exists(spvchain))
+    exec(node, resolve(__dirname, 'chaindb4to6.js'), spvchain);
+})().catch((err) => {
+  console.error(err.stack);
+  process.exit(1);
+});