diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 144fd6ca..bd744c3c 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -7,9 +7,7 @@ updates:
     ignore:
       - dependency-name: dependency-check
       - dependency-name: sinon
-      - dependency-name: airtap
       - dependency-name: nyc
-      - dependency-name: standard
 
       # Pinned to 1.1.10 for browser compatibility (later versions depend
       # on `queue-microtask` which uses arrow functions and promises).
diff --git a/lib/batch.js b/lib/batch.js
index bc43f95d..59565c3e 100644
--- a/lib/batch.js
+++ b/lib/batch.js
@@ -1,7 +1,9 @@
-var WriteError = require('level-errors').WriteError
-var catering = require('catering')
-var getCallback = require('./common').getCallback
-var getOptions = require('./common').getOptions
+'use strict'
+
+const WriteError = require('level-errors').WriteError
+const catering = require('catering')
+const getCallback = require('./common').getCallback
+const getOptions = require('./common').getOptions
 
 function Batch (levelup) {
   // TODO (next major): remove this._levelup alias
@@ -18,7 +20,7 @@ Batch.prototype.put = function (key, value) {
     throw new WriteError(e)
   }
 
-  this.ops.push({ type: 'put', key: key, value: value })
+  this.ops.push({ type: 'put', key, value })
   this.length++
 
   return this
@@ -31,7 +33,7 @@ Batch.prototype.del = function (key) {
     throw new WriteError(err)
   }
 
-  this.ops.push({ type: 'del', key: key })
+  this.ops.push({ type: 'del', key })
   this.length++
 
   return this
@@ -51,8 +53,8 @@ Batch.prototype.clear = function () {
 }
 
 Batch.prototype.write = function (options, callback) {
-  var levelup = this._levelup
-  var ops = this.ops
+  const levelup = this._levelup
+  const ops = this.ops
 
   callback = getCallback(options, callback)
   callback = catering.fromCallback(callback)
diff --git a/lib/common.js b/lib/common.js
index 5096de81..c354fa86 100644
--- a/lib/common.js
+++ b/lib/common.js
@@ -1,3 +1,5 @@
+'use strict'
+
 exports.getCallback = function (options, callback) {
   return typeof options === 'function' ? options : callback
 }
diff --git a/lib/levelup.js b/lib/levelup.js
index 57917dc8..fab316f4 100644
--- a/lib/levelup.js
+++ b/lib/levelup.js
@@ -1,21 +1,23 @@
-var EventEmitter = require('events').EventEmitter
-var inherits = require('util').inherits
-var extend = require('xtend')
-var DeferredLevelDOWN = require('deferred-leveldown')
-var IteratorStream = require('level-iterator-stream')
-var Batch = require('./batch')
-var errors = require('level-errors')
-var supports = require('level-supports')
-var assert = require('assert')
-var catering = require('catering')
-var getCallback = require('./common').getCallback
-var getOptions = require('./common').getOptions
-
-var WriteError = errors.WriteError
-var ReadError = errors.ReadError
-var NotFoundError = errors.NotFoundError
-var OpenError = errors.OpenError
-var InitializationError = errors.InitializationError
+'use strict'
+
+const EventEmitter = require('events').EventEmitter
+const inherits = require('util').inherits
+const extend = require('xtend')
+const DeferredLevelDOWN = require('deferred-leveldown')
+const IteratorStream = require('level-iterator-stream')
+const Batch = require('./batch')
+const errors = require('level-errors')
+const supports = require('level-supports')
+const assert = require('assert')
+const catering = require('catering')
+const getCallback = require('./common').getCallback
+const getOptions = require('./common').getOptions
+
+const WriteError = errors.WriteError
+const ReadError = errors.ReadError
+const NotFoundError = errors.NotFoundError
+const OpenError = errors.OpenError
+const InitializationError = errors.InitializationError
 
 // Possible AbstractLevelDOWN#status values:
 //  - 'new'     - newly created, not opened or closed
@@ -30,8 +32,7 @@ function LevelUP (db, options, callback) {
     return new LevelUP(db, options, callback)
   }
 
-  var error
-  var self = this
+  let error
 
   EventEmitter.call(this)
   this.setMaxListeners(Infinity)
@@ -56,9 +57,9 @@ function LevelUP (db, options, callback) {
   this.options = getOptions(options)
   this._db = db
   this.db = new DeferredLevelDOWN(db)
-  this.open(callback || function (err) {
-    if (err) self.emit('error', err)
-  })
+  this.open(callback || ((err) => {
+    if (err) this.emit('error', err)
+  }))
 
   // Create manifest based on deferred-leveldown's
   this.supports = supports(this.db.supports, {
@@ -70,14 +71,14 @@ function LevelUP (db, options, callback) {
   })
 
   // Experimental: enrich levelup interface
-  Object.keys(this.supports.additionalMethods).forEach(function (method) {
-    if (this[method] != null) return
+  for (const method of Object.keys(this.supports.additionalMethods)) {
+    if (this[method] != null) continue
 
     // Don't do this.db[method].bind() because this.db is dynamic.
-    this[method] = function () {
-      return this.db[method].apply(this.db, arguments)
+    this[method] = function (...args) {
+      return this.db[method](...args)
     }
-  }, this)
+  }
 }
 
 LevelUP.prototype.emit = EventEmitter.prototype.emit
@@ -85,8 +86,6 @@ LevelUP.prototype.once = EventEmitter.prototype.once
 inherits(LevelUP, EventEmitter)
 
 LevelUP.prototype.open = function (opts, callback) {
-  var self = this
-
   if (typeof opts === 'function') {
     callback = opts
     opts = null
@@ -99,39 +98,37 @@ LevelUP.prototype.open = function (opts, callback) {
   }
 
   if (this.isOpen()) {
-    process.nextTick(callback, null, self)
+    process.nextTick(callback, null, this)
     return callback.promise
   }
 
   if (this._isOpening()) {
-    this.once('open', function () { callback(null, self) })
+    this.once('open', () => { callback(null, this) })
     return callback.promise
   }
 
   this.emit('opening')
 
-  this.db.open(opts, function (err) {
+  this.db.open(opts, (err) => {
     if (err) {
       return callback(new OpenError(err))
     }
-    self.db = self._db
-    callback(null, self)
-    self.emit('open')
-    self.emit('ready')
+    this.db = this._db
+    callback(null, this)
+    this.emit('open')
+    this.emit('ready')
   })
 
   return callback.promise
 }
 
 LevelUP.prototype.close = function (callback) {
-  var self = this
-
   callback = catering.fromCallback(callback)
 
   if (this.isOpen()) {
-    this.db.close(function () {
-      self.emit('closed')
-      callback.apply(null, arguments)
+    this.db.close((err, ...rest) => {
+      this.emit('closed')
+      callback(err, ...rest)
     })
     this.emit('closing')
     this.db = new DeferredLevelDOWN(this._db)
@@ -140,8 +137,8 @@ LevelUP.prototype.close = function (callback) {
   } else if (this.db.status === 'closing') {
     this.once('closed', callback)
   } else if (this._isOpening()) {
-    this.once('open', function () {
-      self.close(callback)
+    this.once('open', () => {
+      this.close(callback)
     })
   }
 
@@ -186,8 +183,6 @@ LevelUP.prototype.get = function (key, options, callback) {
 }
 
 LevelUP.prototype.put = function (key, value, options, callback) {
-  var self = this
-
   callback = getCallback(options, callback)
   callback = catering.fromCallback(callback)
 
@@ -197,11 +192,11 @@ LevelUP.prototype.put = function (key, value, options, callback) {
 
   options = getOptions(options)
 
-  this.db.put(key, value, options, function (err) {
+  this.db.put(key, value, options, (err) => {
     if (err) {
       return callback(new WriteError(err))
     }
-    self.emit('put', key, value)
+    this.emit('put', key, value)
     callback()
   })
 
@@ -209,8 +204,6 @@ LevelUP.prototype.put = function (key, value, options, callback) {
 }
 
 LevelUP.prototype.del = function (key, options, callback) {
-  var self = this
-
   callback = getCallback(options, callback)
   callback = catering.fromCallback(callback)
 
@@ -220,11 +213,11 @@ LevelUP.prototype.del = function (key, options, callback) {
 
   options = getOptions(options)
 
-  this.db.del(key, options, function (err) {
+  this.db.del(key, options, (err) => {
     if (err) {
       return callback(new WriteError(err))
     }
-    self.emit('del', key)
+    this.emit('del', key)
     callback()
   })
 
@@ -236,8 +229,6 @@ LevelUP.prototype.batch = function (arr, options, callback) {
     return new Batch(this)
   }
 
-  var self = this
-
   if (typeof arr === 'function') callback = arr
   else callback = getCallback(options, callback)
 
@@ -249,11 +240,11 @@ LevelUP.prototype.batch = function (arr, options, callback) {
 
   options = getOptions(options)
 
-  this.db.batch(arr, options, function (err) {
+  this.db.batch(arr, options, (err) => {
     if (err) {
       return callback(new WriteError(err))
     }
-    self.emit('batch', arr)
+    this.emit('batch', arr)
     callback()
   })
 
@@ -265,8 +256,6 @@ LevelUP.prototype.iterator = function (options) {
 }
 
 LevelUP.prototype.clear = function (options, callback) {
-  var self = this
-
   callback = getCallback(options, callback)
   options = getOptions(options)
   callback = catering.fromCallback(callback)
@@ -275,11 +264,11 @@ LevelUP.prototype.clear = function (options, callback) {
     return callback.promise
   }
 
-  this.db.clear(options, function (err) {
+  this.db.clear(options, (err) => {
     if (err) {
       return callback(new WriteError(err))
     }
-    self.emit('clear', options)
+    this.emit('clear', options)
     callback()
   })
 
diff --git a/package.json b/package.json
index e8cbcd69..446daeda 100644
--- a/package.json
+++ b/package.json
@@ -45,7 +45,7 @@
     "safe-buffer": "^5.1.0",
     "simple-concat": "^1.0.0",
     "sinon": "^7.4.2",
-    "standard": "^15.0.0",
+    "standard": "^16.0.3",
     "tape": "^5.2.2",
     "trickle": "0.0.2"
   },
diff --git a/test/batch-test.js b/test/batch-test.js
index c66a4bd3..0d9a1148 100644
--- a/test/batch-test.js
+++ b/test/batch-test.js
@@ -1,8 +1,8 @@
-var levelup = require('../lib/levelup')
-var errors = levelup.errors
-var each = require('async-each')
-var series = require('run-series')
-var discardable = require('./util/discardable')
+const levelup = require('../lib/levelup')
+const errors = levelup.errors
+const each = require('async-each')
+const series = require('run-series')
+const discardable = require('./util/discardable')
 
 module.exports = function (test, testCommon) {
   test('array-form batch(): multiple puts', function (t) {
@@ -124,11 +124,11 @@ module.exports = function (test, testCommon) {
 
   test('chained batch(): options', function (t) {
     discardable(t, testCommon, function (db, done) {
-      var batch = db.batch()
-      var underlying = batch
+      const batch = db.batch()
+      let underlying = batch
       while (underlying.batch) underlying = underlying.batch
 
-      var write = underlying.write.bind(underlying)
+      const write = underlying.write.bind(underlying)
       underlying.write = function (options, cb) {
         t.same(options, { foo: 'bar' })
         write(options, cb)
@@ -144,9 +144,9 @@ module.exports = function (test, testCommon) {
 
   testCommon.promises && test('chained batch(): promise interface - options', function (t) {
     discardable(t, testCommon, function (db, done) {
-      var batch = db.batch()
+      const batch = db.batch()
 
-      var write = batch.batch.write.bind(batch.batch)
+      const write = batch.batch.write.bind(batch.batch)
       batch.batch.write = function (options, cb) {
         t.same(options, { foo: 'bar' })
         write(options, cb)
@@ -194,7 +194,7 @@ module.exports = function (test, testCommon) {
 
   test('chained batch(): exposes ops queue length', function (t) {
     discardable(t, testCommon, function (db, done) {
-      var batch = db.batch()
+      const batch = db.batch()
         .put('one', '1')
         .del('two')
         .put('three', '3')
@@ -288,7 +288,7 @@ module.exports = function (test, testCommon) {
 
   test('chained batch() arguments', function (t) {
     discardable(t, testCommon, function (db, done) {
-      var batch = db.batch()
+      const batch = db.batch()
 
       t.test('chained batch() arguments: batch#put() with missing `value`', function (t) {
         throws(t, batch.put.bind(batch, 'foo1'), function (err) {
@@ -360,7 +360,7 @@ module.exports = function (test, testCommon) {
         t.is(err.message, 'write() already called on this batch')
       }
 
-      var batch = db.batch()
+      const batch = db.batch()
       batch.put('foo', 'bar').put('boom', 'bang').del('foo').write(function (err) {
         t.ifError(err, 'no batch error')
 
diff --git a/test/benchmarks/engines/levelup-release.js b/test/benchmarks/engines/levelup-release.js
index b30a6c1d..dbfb50b6 100644
--- a/test/benchmarks/engines/levelup-release.js
+++ b/test/benchmarks/engines/levelup-release.js
@@ -1,13 +1,13 @@
-var levelup = require('levelup')
-var leveldown = require('leveldown')
+const levelup = require('levelup')
+const leveldown = require('leveldown')
 
-var createDb = function (location, callback) {
+const createDb = function (location, callback) {
   levelup(leveldown(location), function (err, db) {
     setTimeout(callback.bind(null, err, db), 50)
   })
 }
 
-var closeDb = function (db, callback) {
+const closeDb = function (db, callback) {
   db.close(callback)
 }
 
diff --git a/test/benchmarks/engines/levelup.js b/test/benchmarks/engines/levelup.js
index cddff347..029d8fcb 100644
--- a/test/benchmarks/engines/levelup.js
+++ b/test/benchmarks/engines/levelup.js
@@ -1,13 +1,13 @@
-var levelup = require('../../../')
-var leveldown = require('leveldown')
+const levelup = require('../../../')
+const leveldown = require('leveldown')
 
-var createDb = function (location, callback) {
+const createDb = function (location, callback) {
   levelup(leveldown(location), function (err, db) {
     setTimeout(callback.bind(null, err, db), 50)
   })
 }
 
-var closeDb = function (db, callback) {
+const closeDb = function (db, callback) {
   db.close(callback)
 }
 
diff --git a/test/benchmarks/engines/sqlite3.js b/test/benchmarks/engines/sqlite3.js
index 8fd5b542..8558ae56 100644
--- a/test/benchmarks/engines/sqlite3.js
+++ b/test/benchmarks/engines/sqlite3.js
@@ -1,7 +1,7 @@
-var sqlite3 = require('sqlite3')
+const sqlite3 = require('sqlite3')
 
-var createDb = function (location, callback) {
-  var db = new sqlite3.Database(location, function (err) {
+const createDb = function (location, callback) {
+  const db = new sqlite3.Database(location, function (err) {
     if (err) return callback(err)
     db.run('CREATE TABLE bench (key VARCHAR(32), value TEXT)', function (err) {
       if (err) return callback(err)
@@ -10,7 +10,7 @@ var createDb = function (location, callback) {
   })
 }
 
-var closeDb = function (db, callback) {
+const closeDb = function (db, callback) {
   db.close() // does it have a callback?
   setTimeout(callback, 50)
 }
diff --git a/test/benchmarks/index.js b/test/benchmarks/index.js
index ecac837c..46f25a3a 100644
--- a/test/benchmarks/index.js
+++ b/test/benchmarks/index.js
@@ -1,33 +1,33 @@
-var DB_ROOT = __dirname
-var path = require('path')
-var Benchmark = require('benchmark')
-var rimraf = require('rimraf')
-var async = require('async')
-var engines = require('./engines/')
-var tests = require('./tests/')
+const DB_ROOT = __dirname
+const path = require('path')
+const Benchmark = require('benchmark')
+const rimraf = require('rimraf')
+const async = require('async')
+const engines = require('./engines/')
+let tests = require('./tests/')
 
-var dbidx = 0
+let dbidx = 0
 
-var printableEngineName = function (engineName) {
-  var len = Object.keys(engines).reduce(function (m, c) { return Math.max(c.length, m) }, 0)
+const printableEngineName = function (engineName) {
+  const len = Object.keys(engines).reduce(function (m, c) { return Math.max(c.length, m) }, 0)
   while (engineName.length < len) engineName += ' '
   return engineName
 }
 
-var mklocation = function () {
+const mklocation = function () {
   return path.join(DB_ROOT, '_benchdb_' + dbidx++)
 }
 
-var mkdb = function (engine, location, callback) {
+const mkdb = function (engine, location, callback) {
   rimraf(location, engine.createDb.bind(null, location, callback))
 }
 
-var rmdb = function (engine, db, location, callback) {
+const rmdb = function (engine, db, location, callback) {
   engine.closeDb(db, rimraf.bind(null, location, callback))
 }
 
-var run = function (db, name, fn, color, cb) {
-  var exec = function () {
+const run = function (db, name, fn, color, cb) {
+  const exec = function () {
     new Benchmark(name, {
       defer: true,
       fn: function (deferred) {
@@ -49,11 +49,11 @@ var run = function (db, name, fn, color, cb) {
   } else { exec() }
 }
 
-var runTest = function (testName, callback) {
+const runTest = function (testName, callback) {
   async.forEachSeries(
     Object.keys(engines), function (engineKey, callback) {
-      var engine = engines[engineKey]
-      var location = mklocation()
+      const engine = engines[engineKey]
+      const location = mklocation()
       mkdb(engine, location, function (err, db) {
         if (err) return callback(err)
         if (!tests[testName][engineKey]) { console.log('Skipping for', testName, engineKey); return callback() }
@@ -74,10 +74,10 @@ var runTest = function (testName, callback) {
   )
 }
 
-var focusKey = Object.keys(tests).filter(function (k) { return (/=>/).test(k) })
+const focusKey = Object.keys(tests).filter(function (k) { return (/=>/).test(k) })
 
 if (focusKey.length) {
-  var focusTest = tests[focusKey[0]]
+  const focusTest = tests[focusKey[0]]
   tests = {}
   tests[focusKey[0]] = focusTest
 }
diff --git a/test/benchmarks/stream-bench.js b/test/benchmarks/stream-bench.js
index b52f7e90..aa375530 100644
--- a/test/benchmarks/stream-bench.js
+++ b/test/benchmarks/stream-bench.js
@@ -1,13 +1,13 @@
-var levelup = require(process.argv[2] || '../../')
-var crypto = require('crypto')
-var srcdb = levelup('/tmp/source.db')
+const levelup = require(process.argv[2] || '../../')
+const crypto = require('crypto')
+const srcdb = levelup('/tmp/source.db')
 
-var batch = 10000
-var total = 200000
+const batch = 10000
+const total = 200000
 
 function fillBatch (start, callback) {
-  var b = []
-  for (var i = start; i < start + batch; i++) {
+  const b = []
+  for (let i = start; i < start + batch; i++) {
     b.push({ type: 'put', key: i, value: crypto.randomBytes(100) })
   }
   srcdb.batch(b, callback)
@@ -22,10 +22,10 @@ function populate (start, callback) {
 }
 
 srcdb.on('ready', function () {
-  var start = Date.now()
+  const start = Date.now()
 
   populate(0, function () {
-    var batchTime = Date.now() - start
+    const batchTime = Date.now() - start
     console.log('Filled source! Took %sms, reading data now...', batchTime)
 
     run(function () {
@@ -47,10 +47,10 @@ function run (cb) {
 }
 
 function stream (opts, cb) {
-  var start = Date.now()
+  const start = Date.now()
   srcdb.createReadStream()
     .on('end', function () {
-      var copyTime = Date.now() - start
+      const copyTime = Date.now() - start
       console.log('Done! Took %sms with %j', copyTime, opts)
       if (cb) cb()
     })
diff --git a/test/benchmarks/tests/batch_int_string_x1000_levelup.js b/test/benchmarks/tests/batch_int_string_x1000_levelup.js
index 4214d1a6..7e53965f 100644
--- a/test/benchmarks/tests/batch_int_string_x1000_levelup.js
+++ b/test/benchmarks/tests/batch_int_string_x1000_levelup.js
@@ -1,14 +1,14 @@
-var fn = function (puts, db, cb) {
-  var after = function (err) {
+const fn = function (puts, db, cb) {
+  const after = function (err) {
     if (err) throw err
     cb()
   }
-  var data = []
+  const data = []
 
   if (this.cycle == null) this.cycle = 0
   else this.cycle++
 
-  for (var i = 0; i < puts; i++) {
+  for (let i = 0; i < puts; i++) {
     data.push({
       type: 'put',
       key: this.cycle * puts + i,
diff --git a/test/benchmarks/tests/get_int_string_x1000_levelup.js b/test/benchmarks/tests/get_int_string_x1000_levelup.js
index 107cc2ed..205b979e 100644
--- a/test/benchmarks/tests/get_int_string_x1000_levelup.js
+++ b/test/benchmarks/tests/get_int_string_x1000_levelup.js
@@ -1,7 +1,7 @@
-var setupFn = function (count, db, cb) {
-  var data = []
+const setupFn = function (count, db, cb) {
+  const data = []
 
-  for (var i = 0; i < count; i++) {
+  for (let i = 0; i < count; i++) {
     data.push({
       type: 'put',
       key: String(i),
@@ -12,13 +12,13 @@ var setupFn = function (count, db, cb) {
   db.batch(data, cb)
 }
 
-var fn = function (count, db, cb) {
-  var received = 0
-  var after = function (err) {
+const fn = function (count, db, cb) {
+  let received = 0
+  const after = function (err) {
     if (err) throw err
     if (++received === count) cb()
   }
-  for (var i = 0; i < count; i++) { db.get(String(i), after) }
+  for (let i = 0; i < count; i++) { db.get(String(i), after) }
 }
 
 module.exports = fn.bind(null, 1000)
diff --git a/test/benchmarks/tests/get_int_string_x1000_sqlite3.js b/test/benchmarks/tests/get_int_string_x1000_sqlite3.js
index fb42605c..9f3e0b7b 100644
--- a/test/benchmarks/tests/get_int_string_x1000_sqlite3.js
+++ b/test/benchmarks/tests/get_int_string_x1000_sqlite3.js
@@ -1,7 +1,7 @@
-var async = require('async')
+const async = require('async')
 
-var setupFn = function (count, db, cb) {
-  var queue = async.queue(function (key, callback) {
+const setupFn = function (count, db, cb) {
+  const queue = async.queue(function (key, callback) {
     db.exec(
       'INSERT INTO bench VALUES(' +
         key +
@@ -10,16 +10,16 @@ var setupFn = function (count, db, cb) {
       , callback)
   }, 20)
   queue.drain = cb
-  for (var i = 0; i < count; i++) { queue.push(String(i)) }
+  for (let i = 0; i < count; i++) { queue.push(String(i)) }
 }
 
-var fn = function (count, db, cb) {
-  var received = 0
-  var after = function (err) {
+const fn = function (count, db, cb) {
+  let received = 0
+  const after = function (err) {
     if (err) throw err
     if (++received === count) cb()
   }
-  for (var i = 0; i < count; i++) { db.get('SELECT value FROM bench WHERE key = "' + i + '"', after) }
+  for (let i = 0; i < count; i++) { db.get('SELECT value FROM bench WHERE key = "' + i + '"', after) }
 }
 
 module.exports = fn.bind(null, 1000)
diff --git a/test/benchmarks/tests/put_int_string_x1000_levelup.js b/test/benchmarks/tests/put_int_string_x1000_levelup.js
index 6039fec4..8b7f18c3 100644
--- a/test/benchmarks/tests/put_int_string_x1000_levelup.js
+++ b/test/benchmarks/tests/put_int_string_x1000_levelup.js
@@ -1,6 +1,6 @@
-var fn = function (puts, db, cb) {
-  var received = 0
-  var after = function (err) {
+const fn = function (puts, db, cb) {
+  let received = 0
+  const after = function (err) {
     if (err) throw err
     if (++received === puts) cb()
   }
@@ -8,7 +8,7 @@ var fn = function (puts, db, cb) {
   if (this.cycle == null) this.cycle = 0
   else this.cycle++
 
-  for (var i = 0; i < puts; i++) {
+  for (let i = 0; i < puts; i++) {
     db.put(
       String(this.cycle * puts + i),
       'It\'ll be top end no worries stands out like a bushie. It\'ll be cream no dramas flat out like a rotten. As busy as a slabs bloody built like a stonkered. Get a dog up ya oldies no dramas lets get some bottle-o. Built like a schooner as busy as a big smoke. You little ripper ute my you little ripper dag.',
diff --git a/test/benchmarks/tests/put_int_string_x1000_sqlite3.js b/test/benchmarks/tests/put_int_string_x1000_sqlite3.js
index f24c9e66..7820fded 100644
--- a/test/benchmarks/tests/put_int_string_x1000_sqlite3.js
+++ b/test/benchmarks/tests/put_int_string_x1000_sqlite3.js
@@ -1,6 +1,6 @@
-var fn = function (puts, db, cb) {
-  var received = 0
-  var after = function (err) {
+const fn = function (puts, db, cb) {
+  let received = 0
+  const after = function (err) {
     if (err) throw err
     if (++received === puts) cb()
   }
@@ -8,7 +8,7 @@ var fn = function (puts, db, cb) {
   if (this.cycle == null) this.cycle = 0
   else this.cycle++
 
-  for (var i = 0; i < puts; i++) {
+  for (let i = 0; i < puts; i++) {
     db.exec(
       'INSERT INTO bench VALUES(' +
         String(this.cycle * puts + i) +
diff --git a/test/benchmarks/tests/readStream_x100000_levelup.js b/test/benchmarks/tests/readStream_x100000_levelup.js
index 785da362..1b7cd8ab 100644
--- a/test/benchmarks/tests/readStream_x100000_levelup.js
+++ b/test/benchmarks/tests/readStream_x100000_levelup.js
@@ -1,12 +1,12 @@
-var setupFn = function (count, db, cb) {
-  var doWrites = function () {
+const setupFn = function (count, db, cb) {
+  const doWrites = function () {
     if (--count === 0) return cb()
     db.put('aa' + count, 'bb' + count, doWrites)
   }
   doWrites()
 }
 
-var fn = function (db, cb) {
+const fn = function (db, cb) {
   db.createReadStream().on('end', cb)
 }
 
diff --git a/test/binary-test.js b/test/binary-test.js
index 1ce7fa2b..e46d6147 100644
--- a/test/binary-test.js
+++ b/test/binary-test.js
@@ -1,5 +1,5 @@
-var each = require('async-each')
-var discardable = require('./util/discardable')
+const each = require('async-each')
+const discardable = require('./util/discardable')
 
 module.exports = function (test, testCommon) {
   test('test put() and get() with binary value {valueEncoding:binary}', function (t) {
diff --git a/test/browserify-test.js b/test/browserify-test.js
index 8aaa8bfd..e50e6e97 100644
--- a/test/browserify-test.js
+++ b/test/browserify-test.js
@@ -1,13 +1,13 @@
-var browserify = require('browserify')
-var path = require('path')
-var after = require('after')
-var concat = require('simple-concat')
-var spawn = require('child_process').spawn
-var PACKAGE_JSON = path.join(__dirname, '..', 'package.json')
+const browserify = require('browserify')
+const path = require('path')
+const after = require('after')
+const concat = require('simple-concat')
+const spawn = require('child_process').spawn
+const PACKAGE_JSON = path.join(__dirname, '..', 'package.json')
 
 module.exports = function (test) {
   test('does not contain package.json', function (t) {
-    var b = browserify(path.join(__dirname, '..'), { browserField: true })
+    const b = browserify(path.join(__dirname, '..'), { browserField: true })
       .once('error', t.end.bind(t))
     b.pipeline
       .on('file', function (file, id, parent) {
@@ -17,9 +17,9 @@ module.exports = function (test) {
   })
 
   test('throws error if missing db factory', function (t) {
-    var b = browserify(path.join(__dirname, 'data/browser-throws.js'), { browserField: true })
-    var node = spawn('node')
-    var next = after(2, t.end.bind(t))
+    const b = browserify(path.join(__dirname, 'data/browser-throws.js'), { browserField: true })
+    const node = spawn('node')
+    const next = after(2, t.end.bind(t))
 
     concat(node.stderr, function (err, buf) {
       t.ifError(err)
@@ -36,8 +36,8 @@ module.exports = function (test) {
   })
 
   test('works with valid db factory (memdown)', function (t) {
-    var b = browserify(path.join(__dirname, 'data/browser-works.js'), { browserField: true })
-    var node = spawn('node')
+    const b = browserify(path.join(__dirname, 'data/browser-works.js'), { browserField: true })
+    const node = spawn('node')
     node.on('exit', function (code) {
       t.is(code, 0)
       t.end()
diff --git a/test/clear-test.js b/test/clear-test.js
index c2d7dcd9..7d984aac 100644
--- a/test/clear-test.js
+++ b/test/clear-test.js
@@ -1,13 +1,13 @@
-var memdown = require('memdown')
-var encode = require('encoding-down')
-var concat = require('level-concat-iterator')
-var levelup = require('../lib/levelup')
+const memdown = require('memdown')
+const encode = require('encoding-down')
+const concat = require('level-concat-iterator')
+const levelup = require('../lib/levelup')
 
 module.exports = function (test) {
   test('clear()', function (t) {
     function makeTest (name, fn) {
       t.test(name, function (t) {
-        var mem = memdown()
+        const mem = memdown()
 
         mem.open(function (err) {
           t.ifError(err, 'no open error')
@@ -36,7 +36,7 @@ module.exports = function (test) {
     }
 
     makeTest('clear() without encoding, without deferred-open', function (t, mem) {
-      var db = levelup(mem)
+      const db = levelup(mem)
 
       db.open(function (err) {
         t.ifError(err)
@@ -49,7 +49,7 @@ module.exports = function (test) {
     })
 
     makeTest('clear() without encoding, with deferred-open', function (t, mem) {
-      var db = levelup(mem)
+      const db = levelup(mem)
 
       db.clear({ gte: '"b"' }, function (err) {
         t.ifError(err, 'no clear error')
@@ -58,7 +58,7 @@ module.exports = function (test) {
     })
 
     makeTest('clear() with encoding, with deferred-open', function (t, mem) {
-      var db = levelup(encode(mem, { keyEncoding: 'json' }))
+      const db = levelup(encode(mem, { keyEncoding: 'json' }))
 
       db.clear({ gte: 'b' }, function (err) {
         t.ifError(err, 'no clear error')
@@ -67,7 +67,7 @@ module.exports = function (test) {
     })
 
     makeTest('clear() with encoding, without deferred-open', function (t, mem) {
-      var db = levelup(encode(mem, { keyEncoding: 'json' }))
+      const db = levelup(encode(mem, { keyEncoding: 'json' }))
 
       db.open(function (err) {
         t.ifError(err)
diff --git a/test/common.js b/test/common.js
index 68cad218..a8a9fa16 100644
--- a/test/common.js
+++ b/test/common.js
@@ -1,7 +1,7 @@
 // Same interface as abstract-leveldown's testCommon
 module.exports = function testCommon (options) {
-  var factory = options.factory
-  var test = options.test
+  const factory = options.factory
+  const test = options.test
 
   if (typeof factory !== 'function') {
     throw new TypeError('factory must be a function')
diff --git a/test/create-stream-vs-put-racecondition.js b/test/create-stream-vs-put-racecondition.js
index 6faab6d4..28b18a78 100644
--- a/test/create-stream-vs-put-racecondition.js
+++ b/test/create-stream-vs-put-racecondition.js
@@ -1,7 +1,7 @@
-var levelup = require('../lib/levelup')
-var memdown = require('memdown')
-var encdown = require('encoding-down')
-var after = require('after')
+const levelup = require('../lib/levelup')
+const memdown = require('memdown')
+const encdown = require('encoding-down')
+const after = require('after')
 
 module.exports = function (test, testCommon) {
   ;[true, false].forEach(function (encode) {
@@ -14,7 +14,7 @@ module.exports = function (test, testCommon) {
 }
 
 function makeTest (test, encode, deferredOpen, delayedPut) {
-  var name = [
+  const name = [
     'readStream before put',
     encode && 'encode',
     deferredOpen && 'deferred open',
@@ -22,8 +22,8 @@ function makeTest (test, encode, deferredOpen, delayedPut) {
   ].filter(Boolean).join(', ')
 
   test(name, function (t) {
-    var db = encode ? levelup(encdown(memdown())) : levelup(memdown())
-    var delay = delayedPut ? process.nextTick : callFn
+    const db = encode ? levelup(encdown(memdown())) : levelup(memdown())
+    const delay = delayedPut ? process.nextTick : callFn
 
     run(t, db, !deferredOpen, delay)
   })
@@ -37,8 +37,8 @@ function run (t, db, explicitOpen, delay) {
     })
   }
 
-  var reads = 0
-  var next = after(11, function (err) {
+  let reads = 0
+  const next = after(11, function (err) {
     t.ifError(err, 'no error')
     t.is(reads, 0, 'got 0 items from snaphot')
 
@@ -58,7 +58,7 @@ function run (t, db, explicitOpen, delay) {
 
   // Write data
   delay(function () {
-    for (var i = 0; i < 10; i++) {
+    for (let i = 0; i < 10; i++) {
       db.put(String(i), String(i), next)
     }
   })
diff --git a/test/custom-encoding-test.js b/test/custom-encoding-test.js
index a622d661..39b004b1 100644
--- a/test/custom-encoding-test.js
+++ b/test/custom-encoding-test.js
@@ -1,5 +1,5 @@
-var each = require('async-each')
-var discardable = require('./util/discardable')
+const each = require('async-each')
+const discardable = require('./util/discardable')
 
 module.exports = function (test, testCommon) {
   test('custom encoding: simple-object values in "json" encoding', function (t) {
@@ -61,7 +61,7 @@ module.exports = function (test, testCommon) {
   })
 
   function run (t, entries) {
-    var customEncoding = {
+    const customEncoding = {
       encode: JSON.stringify,
       decode: JSON.parse,
       buffer: false,
@@ -72,7 +72,7 @@ module.exports = function (test, testCommon) {
       keyEncoding: customEncoding,
       valueEncoding: customEncoding
     }, function (db, done) {
-      var ops = entries.map(function (entry) {
+      const ops = entries.map(function (entry) {
         return { type: 'put', key: entry.key, value: entry.value }
       })
 
diff --git a/test/deferred-open-test.js b/test/deferred-open-test.js
index 63c6fe12..b6b465dc 100644
--- a/test/deferred-open-test.js
+++ b/test/deferred-open-test.js
@@ -1,15 +1,15 @@
-var each = require('async-each')
-var parallel = require('run-parallel')
-var concat = require('concat-stream')
-var readStreamContext = require('./util/rs-context')
-var rsFactory = require('./util/rs-factory')
+const each = require('async-each')
+const parallel = require('run-parallel')
+const concat = require('concat-stream')
+const readStreamContext = require('./util/rs-context')
+const rsFactory = require('./util/rs-factory')
 
 module.exports = function (test, testCommon) {
-  var createReadStream = rsFactory(testCommon)
+  const createReadStream = rsFactory(testCommon)
 
   test('deferred open(): put() and get() on new database', function (t) {
     // 1) open database without callback, opens in next tick
-    var db = testCommon.factory()
+    const db = testCommon.factory()
     t.ok(typeof db === 'object' && db !== null)
 
     parallel([
@@ -41,7 +41,7 @@ module.exports = function (test, testCommon) {
 
   test('deferred open(): batch() on new database', function (t) {
     // 1) open database without callback, opens in next tick
-    var db = testCommon.factory()
+    const db = testCommon.factory()
     t.ok(typeof db === 'object' && db !== null)
 
     // 2) insert 3 values with batch(), these should be deferred until the database is actually open
@@ -73,7 +73,7 @@ module.exports = function (test, testCommon) {
 
   test('deferred open(): chained batch() on new database', function (t) {
     // 1) open database without callback, opens in next tick
-    var db = testCommon.factory()
+    const db = testCommon.factory()
     t.ok(typeof db === 'object' && db !== null)
 
     // 2) insert 3 values with batch(), these should be deferred until the database is actually open
@@ -104,14 +104,14 @@ module.exports = function (test, testCommon) {
   })
 
   testCommon.streams && test('deferred open(): test deferred ReadStream', function (t) {
-    var ctx = readStreamContext(t)
-    var db = testCommon.factory()
+    const ctx = readStreamContext(t)
+    const db = testCommon.factory()
 
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
       db.close(function (err) {
         t.ifError(err, 'no error')
-        var async = true
+        let async = true
 
         db.open(function (err) {
           async = false
@@ -134,15 +134,15 @@ module.exports = function (test, testCommon) {
 
   test('deferred open(): no maxListeners warning', function (t) {
     // 1) open database without callback, opens in next tick
-    var db = testCommon.factory()
-    var fail = t.fail.bind(t)
+    const db = testCommon.factory()
+    const fail = t.fail.bind(t)
 
     process.on('warning', fail)
 
     // 2) provoke an EventEmitter maxListeners warning
-    var toPut = 11
+    let toPut = 11
 
-    for (var i = 0; i < toPut; i++) {
+    for (let i = 0; i < toPut; i++) {
       db.put('some', 'string', function (err) {
         t.ifError(err)
         if (!--toPut) {
@@ -154,7 +154,7 @@ module.exports = function (test, testCommon) {
   })
 
   testCommon.encodings && test('deferred open(): value of queued operation is not serialized', function (t) {
-    var db = testCommon.factory({ valueEncoding: 'json' })
+    const db = testCommon.factory({ valueEncoding: 'json' })
 
     // deferred-leveldown < 2.0.2 would serialize the object to a string.
     db.put('key', { thing: 2 }, function (err) {
@@ -169,7 +169,7 @@ module.exports = function (test, testCommon) {
   })
 
   testCommon.encodings && test('deferred open(): key of queued operation is not serialized', function (t) {
-    var db = testCommon.factory({ keyEncoding: 'json' })
+    const db = testCommon.factory({ keyEncoding: 'json' })
 
     // deferred-leveldown < 2.0.2 would serialize the key to a string.
     db.put({ thing: 2 }, 'value', function (err) {
diff --git a/test/get-put-del-test.js b/test/get-put-del-test.js
index c624193c..16da7f0b 100644
--- a/test/get-put-del-test.js
+++ b/test/get-put-del-test.js
@@ -1,7 +1,7 @@
-var errors = require('../lib/levelup').errors
-var each = require('async-each')
-var series = require('run-series')
-var discardable = require('./util/discardable')
+const errors = require('../lib/levelup').errors
+const each = require('async-each')
+const series = require('run-series')
+const discardable = require('./util/discardable')
 
 module.exports = function (test, testCommon) {
   test('get() / put() / del(): get() on empty database causes error', function (t) {
diff --git a/test/idempotent-test.js b/test/idempotent-test.js
index 2b90d424..01159ea4 100644
--- a/test/idempotent-test.js
+++ b/test/idempotent-test.js
@@ -1,14 +1,14 @@
-var levelup = require('../lib/levelup.js')
-var memdown = require('memdown')
-var sinon = require('sinon')
+const levelup = require('../lib/levelup.js')
+const memdown = require('memdown')
+const sinon = require('sinon')
 
 module.exports = function (test, testCommon) {
   test('call open twice, should emit "open" once', function (t) {
-    var n = 0
-    var m = 0
-    var db
-    var close = function () {
-      var closing = sinon.spy()
+    let n = 0
+    let m = 0
+
+    const close = function () {
+      const closing = sinon.spy()
       db.on('closing', closing)
       db.on('closed', function () {
         t.is(closing.callCount, 1)
@@ -21,7 +21,7 @@ module.exports = function (test, testCommon) {
       process.nextTick(db.close.bind(db))
     }
 
-    db = levelup(memdown(), function () {
+    const db = levelup(memdown(), function () {
       t.is(n++, 0, 'callback should fire only once')
       if (n && m) { close() }
     })
diff --git a/test/index.js b/test/index.js
index 55fc2a47..6babda94 100644
--- a/test/index.js
+++ b/test/index.js
@@ -1,10 +1,10 @@
 'use strict'
 
-var common = require('./common')
+const common = require('./common')
 
 function suite (options) {
-  var testCommon = common(options)
-  var test = testCommon.test
+  const testCommon = common(options)
+  const test = testCommon.test
 
   require('./manifest-test')(test, testCommon)
   require('./batch-test')(test, testCommon)
diff --git a/test/init-test.js b/test/init-test.js
index eb114aa7..24078341 100644
--- a/test/init-test.js
+++ b/test/init-test.js
@@ -1,5 +1,5 @@
-var levelup = require('../lib/levelup')
-var memdown = require('memdown')
+const levelup = require('../lib/levelup')
+const memdown = require('memdown')
 
 module.exports = function (test, testCommon) {
   test('Init & open(): levelup()', function (t) {
@@ -38,7 +38,7 @@ module.exports = function (test, testCommon) {
   })
 
   test('Init & open(): without callback', function (t) {
-    var db = levelup(memdown())
+    const db = levelup(memdown())
     t.ok(typeof db === 'object' && db !== null)
     db.on('ready', function () {
       t.is(db.isOpen(), true)
@@ -49,7 +49,7 @@ module.exports = function (test, testCommon) {
   test('Init & open(): error with callback', function (t) {
     t.plan(1)
 
-    var mem = memdown()
+    const mem = memdown()
     mem._open = function (opts, cb) {
       process.nextTick(cb, new Error('from underlying store'))
     }
@@ -66,7 +66,7 @@ module.exports = function (test, testCommon) {
   test('Init & open(): error without callback', function (t) {
     t.plan(1)
 
-    var mem = memdown()
+    const mem = memdown()
     mem._open = function (opts, cb) {
       process.nextTick(cb, new Error('from underlying store'))
     }
@@ -83,7 +83,7 @@ module.exports = function (test, testCommon) {
   test('Init & open(): validate abstract-leveldown', function (t) {
     t.plan(1)
 
-    var down = memdown()
+    const down = memdown()
 
     Object.defineProperty(down, 'status', {
       get: function () { return null },
@@ -98,7 +98,7 @@ module.exports = function (test, testCommon) {
   })
 
   test('Init & open(): support open options', function (t) {
-    var down = memdown()
+    const down = memdown()
 
     levelup(down, function (err, up) {
       t.ifError(err, 'no error')
diff --git a/test/iterator-seek-test.js b/test/iterator-seek-test.js
index edf0dca7..ead23931 100644
--- a/test/iterator-seek-test.js
+++ b/test/iterator-seek-test.js
@@ -1,10 +1,10 @@
-var memdown = require('memdown')
-var encode = require('encoding-down')
-var levelup = require('../lib/levelup')
+const memdown = require('memdown')
+const encode = require('encoding-down')
+const levelup = require('../lib/levelup')
 
 module.exports = function (test, testCommon) {
   test('iterator#seek()', function (t) {
-    var mem = memdown()
+    const mem = memdown()
 
     t.test('setup', function (t) {
       mem.open(function (err) {
@@ -20,12 +20,12 @@ module.exports = function (test, testCommon) {
     })
 
     t.test('without encoding, without deferred-open', function (t) {
-      var db = levelup(mem)
+      const db = levelup(mem)
 
       db.open(function (err) {
         t.ifError(err, 'no open error')
 
-        var it = db.iterator({ keyAsBuffer: false })
+        const it = db.iterator({ keyAsBuffer: false })
 
         it.seek('"b"')
         it.next(function (err, key, value) {
@@ -40,8 +40,8 @@ module.exports = function (test, testCommon) {
     })
 
     t.test('without encoding, with deferred-open', function (t) {
-      var db = levelup(mem)
-      var it = db.iterator({ keyAsBuffer: false })
+      const db = levelup(mem)
+      const it = db.iterator({ keyAsBuffer: false })
 
       it.seek('"b"')
       it.next(function (err, key, value) {
@@ -55,8 +55,8 @@ module.exports = function (test, testCommon) {
     })
 
     t.test('with encoding, with deferred-open', function (t) {
-      var db = levelup(encode(mem, { keyEncoding: 'json' }))
-      var it = db.iterator()
+      const db = levelup(encode(mem, { keyEncoding: 'json' }))
+      const it = db.iterator()
 
       it.seek('b')
       it.next(function (err, key, value) {
@@ -70,12 +70,12 @@ module.exports = function (test, testCommon) {
     })
 
     t.test('with encoding, without deferred-open', function (t) {
-      var db = levelup(encode(mem, { keyEncoding: 'json' }))
+      const db = levelup(encode(mem, { keyEncoding: 'json' }))
 
       db.open(function (err) {
         t.ifError(err, 'no open error')
 
-        var it = db.iterator()
+        const it = db.iterator()
 
         it.seek('b')
         it.next(function (err, key, value) {
diff --git a/test/iterator-test.js b/test/iterator-test.js
index 01e50f70..88d6db47 100644
--- a/test/iterator-test.js
+++ b/test/iterator-test.js
@@ -1,14 +1,14 @@
-var memdown = require('memdown')
-var levelup = require('../lib/levelup')
+const memdown = require('memdown')
+const levelup = require('../lib/levelup')
 
 module.exports = function (test, testCommon) {
   test('simple iterator without encoding-down', function (t) {
-    var db = levelup(memdown())
+    const db = levelup(memdown())
 
     db.put('key', 'value', function (err) {
       t.ifError(err, 'no put error')
 
-      var it = db.iterator({
+      const it = db.iterator({
         keyAsBuffer: false,
         valueAsBuffer: false
       })
diff --git a/test/json-encoding-test.js b/test/json-encoding-test.js
index ef05e6c9..bcbbda76 100644
--- a/test/json-encoding-test.js
+++ b/test/json-encoding-test.js
@@ -1,8 +1,8 @@
-var each = require('async-each')
-var parallel = require('run-parallel')
-var concatStream = require('concat-stream')
-var concatIterator = require('level-concat-iterator')
-var discardable = require('./util/discardable')
+const each = require('async-each')
+const parallel = require('run-parallel')
+const concatStream = require('concat-stream')
+const concatIterator = require('level-concat-iterator')
+const discardable = require('./util/discardable')
 
 module.exports = function (test, testCommon) {
   test('json encoding: simple-object values in "json" encoding', function (t) {
@@ -56,7 +56,7 @@ module.exports = function (test, testCommon) {
       keyEncoding: 'json',
       valueEncoding: 'json'
     }, function (db, done) {
-      var ops = entries.map(function (entry) {
+      const ops = entries.map(function (entry) {
         return { type: 'put', key: entry.key, value: entry.value }
       })
 
diff --git a/test/key-value-streams-test.js b/test/key-value-streams-test.js
index aef0a35a..20d5e368 100644
--- a/test/key-value-streams-test.js
+++ b/test/key-value-streams-test.js
@@ -1,15 +1,15 @@
-var sinon = require('sinon')
-var discardable = require('./util/discardable')
+const sinon = require('sinon')
+const discardable = require('./util/discardable')
 
 module.exports = function (test, testCommon) {
   test('key and value streams: keyStream()', function (t) {
-    var ctx = createContext(t)
+    const ctx = createContext(t)
 
     discardable(t, testCommon, function (db, done) {
       db.batch(ctx.sourceData.slice(), function (err) {
         t.ifError(err)
 
-        var rs = db.keyStream()
+        const rs = db.keyStream()
         rs.on('data', ctx.dataSpy)
         rs.on('end', ctx.endSpy)
         rs.on('close', function () {
@@ -21,13 +21,13 @@ module.exports = function (test, testCommon) {
   })
 
   test('key and value streams: readStream({keys:true,values:false})', function (t) {
-    var ctx = createContext(t)
+    const ctx = createContext(t)
 
     discardable(t, testCommon, function (db, done) {
       db.batch(ctx.sourceData.slice(), function (err) {
         t.ifError(err)
 
-        var rs = db.readStream({ keys: true, values: false })
+        const rs = db.readStream({ keys: true, values: false })
         rs.on('data', ctx.dataSpy)
         rs.on('end', ctx.endSpy)
         rs.on('close', function () {
@@ -39,13 +39,13 @@ module.exports = function (test, testCommon) {
   })
 
   test('key and value streams: valueStream()', function (t) {
-    var ctx = createContext(t)
+    const ctx = createContext(t)
 
     discardable(t, testCommon, function (db, done) {
       db.batch(ctx.sourceData.slice(), function (err) {
         t.ifError(err)
 
-        var rs = db.valueStream()
+        const rs = db.valueStream()
         rs.on('data', ctx.dataSpy)
         rs.on('end', ctx.endSpy)
         rs.on('close', function () {
@@ -57,13 +57,13 @@ module.exports = function (test, testCommon) {
   })
 
   test('key and value streams: readStream({keys:false,values:true})', function (t) {
-    var ctx = createContext(t)
+    const ctx = createContext(t)
 
     discardable(t, testCommon, function (db, done) {
       db.batch(ctx.sourceData.slice(), function (err) {
         t.ifError(err)
 
-        var rs = db.readStream({ keys: false, values: true })
+        const rs = db.readStream({ keys: false, values: true })
         rs.on('data', ctx.dataSpy)
         rs.on('end', ctx.endSpy)
         rs.on('close', function () {
@@ -76,14 +76,14 @@ module.exports = function (test, testCommon) {
 }
 
 function createContext (t) {
-  var ctx = {}
+  const ctx = {}
 
   ctx.dataSpy = sinon.spy()
   ctx.endSpy = sinon.spy()
   ctx.sourceData = []
 
-  for (var i = 0; i < 100; i++) {
-    var k = (i < 10 ? '0' : '') + i
+  for (let i = 0; i < 100; i++) {
+    const k = (i < 10 ? '0' : '') + i
     ctx.sourceData.push({
       type: 'put',
       key: k,
@@ -101,7 +101,7 @@ function createContext (t) {
     t.is(ctx.dataSpy.callCount, data.length, 'stream emitted correct number of "data" events')
 
     data.forEach(function (d, i) {
-      var call = ctx.dataSpy.getCall(i)
+      const call = ctx.dataSpy.getCall(i)
 
       if (call) {
         t.is(call.args.length, 1, 'stream "data" event #' + i + ' fired with 1 argument')
diff --git a/test/manifest-test.js b/test/manifest-test.js
index fa3704ea..011491ba 100644
--- a/test/manifest-test.js
+++ b/test/manifest-test.js
@@ -1,11 +1,11 @@
-var suite = require('level-supports/test')
+const suite = require('level-supports/test')
 
 module.exports = function (test, testCommon) {
   suite(test, testCommon)
 
   // TODO (once manifest lands in other modules): add integration tests.
   test('manifest has expected properties', function (t) {
-    var db = testCommon.factory()
+    const db = testCommon.factory()
 
     t.is(db.supports.status, false)
     t.is(db.supports.deferredOpen, true)
diff --git a/test/maybe-error-test.js b/test/maybe-error-test.js
index b07613b5..5ecf4fb5 100644
--- a/test/maybe-error-test.js
+++ b/test/maybe-error-test.js
@@ -1,13 +1,13 @@
 'use strict'
 
-var discardable = require('./util/discardable')
+const discardable = require('./util/discardable')
 
 module.exports = function (test, testCommon) {
   test('maybeError() should be called async: put()', function (t) {
     discardable(t, testCommon, function (db, done) {
       db.close(function () {
         t.is(db.isClosed(), true, 'db is closed')
-        var sync = false
+        let sync = false
         db.put('key', 'value', {}, function (err) {
           sync = true
           t.ok(err)
@@ -25,7 +25,7 @@ module.exports = function (test, testCommon) {
         t.ifError(err)
         db.close(function () {
           t.is(db.isClosed(), true, 'db is closed')
-          var sync = false
+          let sync = false
           db.get('key', {}, function (err, value) {
             sync = true
             t.ok(err)
@@ -44,7 +44,7 @@ module.exports = function (test, testCommon) {
         t.ifError(err)
         db.close(function () {
           t.is(db.isClosed(), true, 'db is closed')
-          var sync = false
+          let sync = false
           db.del('key', {}, function (err) {
             sync = true
             t.ok(err)
@@ -61,7 +61,7 @@ module.exports = function (test, testCommon) {
     discardable(t, testCommon, function (db, done) {
       db.close(function () {
         t.is(db.isClosed(), true, 'db is closed')
-        var sync = false
+        let sync = false
         db.batch([{ type: 'put', key: 'key' }], {}, function (err) {
           sync = true
           t.ok(err)
diff --git a/test/no-encoding-test.js b/test/no-encoding-test.js
index fd216eb8..ce313602 100644
--- a/test/no-encoding-test.js
+++ b/test/no-encoding-test.js
@@ -1,15 +1,15 @@
-var levelup = require('../lib/levelup')
-var memdown = require('memdown')
+const levelup = require('../lib/levelup')
+const memdown = require('memdown')
 
 module.exports = function (test, testCommon) {
   test('without encoding-down: serializes key', function (t) {
-    var down = memdown()
+    const down = memdown()
 
     down._serializeKey = function (key) {
       return key.toUpperCase()
     }
 
-    var db = levelup(down)
+    const db = levelup(down)
 
     db.put('key', 'value', function (err) {
       t.ifError(err)
@@ -23,13 +23,13 @@ module.exports = function (test, testCommon) {
   })
 
   test('without encoding-down: serializes value', function (t) {
-    var down = memdown()
+    const down = memdown()
 
     down._serializeValue = function (value) {
       return value.toUpperCase()
     }
 
-    var db = levelup(down)
+    const db = levelup(down)
 
     db.put('key', 'value', function (err) {
       t.ifError(err)
diff --git a/test/null-and-undefined-test.js b/test/null-and-undefined-test.js
index 1ea4e30f..65b9e00c 100644
--- a/test/null-and-undefined-test.js
+++ b/test/null-and-undefined-test.js
@@ -1,10 +1,10 @@
-var after = require('after')
-var discardable = require('./util/discardable')
+const after = require('after')
+const discardable = require('./util/discardable')
 
 module.exports = function (test, testCommon) {
   test('null & undefined keys & values: cause error', function (t) {
     discardable(t, testCommon, function (db, done) {
-      var next = after(12, done)
+      const next = after(12, done)
 
       ;[null, undefined].forEach(function (nullish) {
         db.get(nullish, function (err) {
diff --git a/test/open-patchsafe-test.js b/test/open-patchsafe-test.js
index 178c6e3a..5aef341c 100644
--- a/test/open-patchsafe-test.js
+++ b/test/open-patchsafe-test.js
@@ -1,7 +1,7 @@
 module.exports = function (test, testCommon) {
   test('deferred open() is patch-safe: put() on new database', makeTest(function (t, db, done) {
-    var put = db.put
-    var called = 0
+    const put = db.put
+    let called = 0
 
     db.put = function () {
       called++
@@ -15,8 +15,8 @@ module.exports = function (test, testCommon) {
   }))
 
   test('deferred open() is patch-safe: del() on new database', makeTest(function (t, db, done) {
-    var del = db.del
-    var called = 0
+    const del = db.del
+    let called = 0
 
     db.del = function () {
       called++
@@ -30,8 +30,8 @@ module.exports = function (test, testCommon) {
   }))
 
   test('deferred open() is patch-safe: batch() on new database', makeTest(function (t, db, done) {
-    var batch = db.batch
-    var called = 0
+    const batch = db.batch
+    let called = 0
 
     db.batch = function () {
       called++
@@ -50,7 +50,7 @@ module.exports = function (test, testCommon) {
   function makeTest (fn) {
     return function (t) {
       // 1) open database without callback, opens in next tick
-      var db = testCommon.factory()
+      const db = testCommon.factory()
 
       fn(t, db, function (err) {
         t.ifError(err, 'no test error')
diff --git a/test/read-stream-test.js b/test/read-stream-test.js
index 3f3cb179..b1e9dcef 100644
--- a/test/read-stream-test.js
+++ b/test/read-stream-test.js
@@ -1,11 +1,11 @@
-var sinon = require('sinon')
-var bigBlob = Array.apply(null, Array(1024 * 100)).map(function () { return 'aaaaaaaaaa' }).join('')
-var discardable = require('./util/discardable')
-var readStreamContext = require('./util/rs-context')
-var rsFactory = require('./util/rs-factory')
+const sinon = require('sinon')
+const bigBlob = Array.apply(null, Array(1024 * 100)).map(function () { return 'aaaaaaaaaa' }).join('')
+const discardable = require('./util/discardable')
+const readStreamContext = require('./util/rs-context')
+const rsFactory = require('./util/rs-factory')
 
 module.exports = function (test, testCommon) {
-  var createReadStream = rsFactory(testCommon)
+  const createReadStream = rsFactory(testCommon)
 
   function makeTest (fn) {
     return function (t) {
@@ -19,7 +19,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db)
+      const rs = createReadStream(db)
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -30,14 +30,15 @@ module.exports = function (test, testCommon) {
   }))
 
   test('ReadStream: pausing', makeTest(function (t, db, ctx, done) {
-    var calls = 0
-    var rs
-    var pauseVerify = function () {
+    let calls = 0
+    let rs
+
+    const pauseVerify = function () {
       t.is(calls, 5, 'stream should still be paused')
       rs.resume()
       pauseVerify.called = true
     }
-    var onData = function () {
+    const onData = function () {
       if (++calls === 5) {
         rs.pause()
         setTimeout(pauseVerify, 50)
@@ -66,7 +67,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db)
+      const rs = createReadStream(db)
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -82,7 +83,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db)
+      const rs = createReadStream(db)
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -97,7 +98,7 @@ module.exports = function (test, testCommon) {
       t.ifError(err)
       db.close(function (err) {
         t.ifError(err)
-        var rs = createReadStream(db)
+        const rs = createReadStream(db)
         rs.destroy()
         done()
       })
@@ -108,7 +109,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db)
+      const rs = createReadStream(db)
       rs.on('data', function () {
         rs.destroy()
         rs.destroy()
@@ -121,9 +122,9 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db)
-      var endSpy = sinon.spy()
-      var calls = 0
+      const rs = createReadStream(db)
+      const endSpy = sinon.spy()
+      let calls = 0
       ctx.dataSpy = sinon.spy(function () {
         if (++calls === 5) { rs.destroy() }
       })
@@ -134,7 +135,7 @@ module.exports = function (test, testCommon) {
         t.is(ctx.dataSpy.callCount, 5, 'ReadStream emitted correct number of "data" events (5)')
 
         ctx.sourceData.slice(0, 5).forEach(function (d, i) {
-          var call = ctx.dataSpy.getCall(i)
+          const call = ctx.dataSpy.getCall(i)
           t.ok(call)
 
           if (call) {
@@ -155,7 +156,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { reverse: true })
+      const rs = createReadStream(db, { reverse: true })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -169,7 +170,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { start: '50' })
+      const rs = createReadStream(db, { start: '50' })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -184,7 +185,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { start: '50', reverse: true })
+      const rs = createReadStream(db, { start: '50', reverse: true })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -200,7 +201,7 @@ module.exports = function (test, testCommon) {
       t.ifError(err)
 
       // '49.5' doesn't actually exist but we expect it to start at '50' because '49' < '49.5' < '50' (in string terms as well as numeric)
-      var rs = createReadStream(db, { start: '49.5' })
+      const rs = createReadStream(db, { start: '49.5' })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -215,7 +216,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { start: '49.5', reverse: true })
+      const rs = createReadStream(db, { start: '49.5', reverse: true })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -232,7 +233,7 @@ module.exports = function (test, testCommon) {
 
       // '499999' doesn't actually exist but we expect it to start at '50' because '49' < '499999' < '50' (in string terms)
       // the same as the previous test but we're relying solely on string ordering
-      var rs = createReadStream(db, { start: '499999' })
+      const rs = createReadStream(db, { start: '499999' })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -247,7 +248,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { end: '50' })
+      const rs = createReadStream(db, { end: '50' })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -262,7 +263,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { end: '50.5' })
+      const rs = createReadStream(db, { end: '50.5' })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -277,7 +278,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { end: '50555555' })
+      const rs = createReadStream(db, { end: '50555555' })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -292,7 +293,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { end: '50.5', reverse: true })
+      const rs = createReadStream(db, { end: '50.5', reverse: true })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -306,7 +307,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { start: 30, end: 70 })
+      const rs = createReadStream(db, { start: 30, end: 70 })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -321,7 +322,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { start: 70, end: 30, reverse: true })
+      const rs = createReadStream(db, { start: 70, end: 30, reverse: true })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -334,15 +335,15 @@ module.exports = function (test, testCommon) {
 
   // TODO: move this test out
   testCommon.encodings && test('ReadStream: hex encoding', makeTest(function (t, db, ctx, done) {
-    var options = { keyEncoding: 'utf8', valueEncoding: 'hex' }
-    var data = [
+    const options = { keyEncoding: 'utf8', valueEncoding: 'hex' }
+    const data = [
       { type: 'put', key: 'ab', value: 'abcdef0123456789' }
     ]
 
     db.batch(data.slice(), options, function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, options)
+      const rs = createReadStream(db, options)
       rs.on('data', function (data) {
         t.is(data.value, 'abcdef0123456789')
       })
@@ -355,10 +356,10 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
       // read in reverse, assume all's good
-      var rs = createReadStream(db, { reverse: true })
+      const rs = createReadStream(db, { reverse: true })
       rs.on('close', function () {
         // now try reading the other way
-        var rs = createReadStream(db)
+        const rs = createReadStream(db)
         rs.on('data', ctx.dataSpy)
         rs.on('end', ctx.endSpy)
         rs.on('close', function () {
@@ -374,7 +375,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { start: 0 })
+      const rs = createReadStream(db, { start: 0 })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -390,7 +391,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { end: 0 })
+      const rs = createReadStream(db, { end: 0 })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -404,15 +405,15 @@ module.exports = function (test, testCommon) {
   // i.e. not waiting for 'open' to complete
   // TODO: move this test out
   testCommon.deferredOpen && test('ReadStream: deferred ReadStream on new db', function (t) {
-    var db = testCommon.factory()
-    var ctx = readStreamContext(t)
+    const db = testCommon.factory()
+    const ctx = readStreamContext(t)
 
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
       db.close(function (err) {
         t.ifError(err)
 
-        var async = true
+        let async = true
         db.open(function (err) {
           async = false
           t.ifError(err, 'no open error')
@@ -422,7 +423,7 @@ module.exports = function (test, testCommon) {
         t.is(db.isOpen(), false)
         t.is(db.isClosed(), false)
 
-        var rs = createReadStream(db)
+        const rs = createReadStream(db)
         rs.on('data', ctx.dataSpy)
         rs.on('end', ctx.endSpy)
         rs.on('close', function () {
@@ -440,7 +441,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { limit: 20 })
+      const rs = createReadStream(db, { limit: 20 })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -454,7 +455,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { start: '20', limit: 20 })
+      const rs = createReadStream(db, { start: '20', limit: 20 })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -468,7 +469,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { end: '50', limit: 20 })
+      const rs = createReadStream(db, { end: '50', limit: 20 })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -482,7 +483,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db, { end: '30', limit: 50 })
+      const rs = createReadStream(db, { end: '30', limit: 50 })
       rs.on('data', ctx.dataSpy)
       rs.on('end', ctx.endSpy)
       rs.on('close', function () {
@@ -497,9 +498,9 @@ module.exports = function (test, testCommon) {
   // the use of large blobs means that next() takes time to return
   // so we should be able to slip in an end() while it's working
   test('ReadStream: iterator next/end race condition', makeTest(function (t, db, ctx, done) {
-    var data = []
-    var i = 5
-    var v
+    const data = []
+    let i = 5
+    let v
 
     while (i--) {
       v = bigBlob + i
@@ -508,7 +509,7 @@ module.exports = function (test, testCommon) {
 
     db.batch(data, function (err) {
       t.ifError(err)
-      var rs = createReadStream(db).on('close', done)
+      const rs = createReadStream(db).on('close', done)
       rs.once('data', function () {
         rs.destroy()
       })
@@ -519,7 +520,7 @@ module.exports = function (test, testCommon) {
     db.batch(ctx.sourceData.slice(), function (err) {
       t.ifError(err)
 
-      var rs = createReadStream(db)
+      const rs = createReadStream(db)
         .on('close', done)
 
       process.nextTick(function () {
diff --git a/test/self.js b/test/self.js
index 7ccf3bc1..d8e97f38 100644
--- a/test/self.js
+++ b/test/self.js
@@ -5,12 +5,12 @@ if (process.browser && typeof Promise !== 'function') {
   global.Promise = require('pinkie')
 }
 
-var test = require('tape')
-var memdown = require('memdown')
-var encode = require('encoding-down')
-var levelup = require('../lib/levelup')
-var suite = require('.')
-var noop = function () {}
+const test = require('tape')
+const memdown = require('memdown')
+const encode = require('encoding-down')
+const levelup = require('../lib/levelup')
+const suite = require('.')
+const noop = function () {}
 
 suite({
   test: test,
diff --git a/test/self/manifest-test.js b/test/self/manifest-test.js
index 2ab94c62..5945ddaf 100644
--- a/test/self/manifest-test.js
+++ b/test/self/manifest-test.js
@@ -1,17 +1,17 @@
 'use strict'
 
-var test = require('tape')
-var levelup = require('../..')
-var memdown = require('memdown')
-var sinon = require('sinon')
+const test = require('tape')
+const levelup = require('../..')
+const memdown = require('memdown')
+const sinon = require('sinon')
 
 test('manifest: additionalMethod is proxied', function (t) {
-  var mem = memdown()
+  const mem = memdown()
 
   mem.beep = sinon.spy()
   mem.supports = { additionalMethods: { beep: true } }
 
-  var db = levelup(mem)
+  const db = levelup(mem)
 
   t.is(typeof db.beep, 'function')
   t.is(typeof levelup.prototype.beep, 'undefined')
@@ -31,9 +31,9 @@ test('manifest: additionalMethod is proxied', function (t) {
 })
 
 test('manifest: additionalMethod is proxied even if function does not exist', function (t) {
-  var mem = memdown()
+  const mem = memdown()
   mem.supports = { additionalMethods: { beep: true } }
-  var db = levelup(mem)
+  const db = levelup(mem)
 
   t.is(typeof db.beep, 'function')
   t.is(typeof levelup.prototype.beep, 'undefined')
@@ -41,7 +41,7 @@ test('manifest: additionalMethod is proxied even if function does not exist', fu
 })
 
 test('manifest: approximateSize() et al are proxied even if manifest does not exist', function (t) {
-  var mem = memdown()
+  const mem = memdown()
 
   // deferred-leveldown should feature-detect these methods (for now)
   mem.approximateSize = function () {}
@@ -50,7 +50,7 @@ test('manifest: approximateSize() et al are proxied even if manifest does not ex
   mem.otherMethod = function () {}
   mem.supports = null
 
-  var db = levelup(mem)
+  const db = levelup(mem)
 
   t.is(typeof db.approximateSize, 'function')
   t.is(typeof db.compactRange, 'function')
diff --git a/test/snapshot-test.js b/test/snapshot-test.js
index f216d33c..5f89108a 100644
--- a/test/snapshot-test.js
+++ b/test/snapshot-test.js
@@ -1,15 +1,15 @@
-var delayed = require('delayed').delayed
-var trickle = require('trickle')
-var discardable = require('./util/discardable')
-var readStreamContext = require('./util/rs-context')
-var rsFactory = require('./util/rs-factory')
+const delayed = require('delayed').delayed
+const trickle = require('trickle')
+const discardable = require('./util/discardable')
+const readStreamContext = require('./util/rs-context')
+const rsFactory = require('./util/rs-factory')
 
 module.exports = function (test, testCommon) {
-  var createReadStream = rsFactory(testCommon)
+  const createReadStream = rsFactory(testCommon)
 
   test('ReadStream implicit snapshot', function (t) {
     discardable(t, testCommon, function (db, done) {
-      var ctx = readStreamContext(t)
+      const ctx = readStreamContext(t)
 
       // 1) Store 100 random numbers stored in the database
       db.batch(ctx.sourceData.slice(), function (err) {
@@ -19,7 +19,7 @@ module.exports = function (test, testCommon) {
         //    to make *sure* that we're going to be reading it for longer than it
         //    takes to overwrite the data in there.
 
-        var rs = createReadStream(db).pipe(trickle({ interval: 5 }))
+        const rs = createReadStream(db).pipe(trickle({ interval: 5 }))
 
         rs.on('data', ctx.dataSpy)
         rs.once('end', ctx.endSpy)
@@ -33,9 +33,9 @@ module.exports = function (test, testCommon) {
           //    If we're not using a snapshot then then we'd expect the test
           //    to fail because it'll pick up these new values rather than the
           //    old ones.
-          var newData = []
-          var i
-          var k
+          const newData = []
+          let i
+          let k
 
           for (i = 0; i < 100; i++) {
             k = (i < 10 ? '0' : '') + i
diff --git a/test/util/discardable.js b/test/util/discardable.js
index 53fecd06..aa1e3828 100644
--- a/test/util/discardable.js
+++ b/test/util/discardable.js
@@ -4,7 +4,7 @@ module.exports = function discardable (t, testCommon, options, fn) {
     options = {}
   }
 
-  var db = testCommon.factory(options)
+  const db = testCommon.factory(options)
 
   db.open(function () {
     fn(db, function done (err) {
diff --git a/test/util/rs-context.js b/test/util/rs-context.js
index 00869ffa..c42b6440 100644
--- a/test/util/rs-context.js
+++ b/test/util/rs-context.js
@@ -1,11 +1,11 @@
 'use strict'
 
-var sinon = require('sinon')
+const sinon = require('sinon')
 
 module.exports = function readStreamContext (t) {
-  var ctx = {}
-  var i
-  var k
+  const ctx = {}
+  let i
+  let k
 
   ctx.dataSpy = sinon.spy()
   ctx.endSpy = sinon.spy()
@@ -27,7 +27,7 @@ module.exports = function readStreamContext (t) {
     t.is(ctx.dataSpy.callCount, data.length, 'ReadStream emitted correct number of "data" events')
 
     data.forEach(function (d, i) {
-      var call = ctx.dataSpy.getCall(i)
+      const call = ctx.dataSpy.getCall(i)
       if (call) {
         t.is(call.args.length, 1, 'ReadStream "data" event #' + i + ' fired with 1 argument')
         t.ok(call.args[0].key, 'ReadStream "data" event #' + i + ' argument has "key" property')
diff --git a/test/util/rs-factory.js b/test/util/rs-factory.js
index 0396da88..2cfa7dbf 100644
--- a/test/util/rs-factory.js
+++ b/test/util/rs-factory.js
@@ -1,6 +1,6 @@
 'use strict'
 
-var xtend = require('xtend')
+const xtend = require('xtend')
 
 module.exports = function (testCommon) {
   return function createReadStream (db, options) {