diff --git a/src/address.js b/src/address.js
index 221f85a..949e389 100644
--- a/src/address.js
+++ b/src/address.js
@@ -1,11 +1,11 @@
-var Buffer = require('safe-buffer').Buffer
-var bech32 = require('bech32')
-var bs58check = require('bs58check')
-var bscript = require('./script')
-var btemplates = require('./templates')
-var networks = require('./networks')
-var typeforce = require('typeforce')
-var types = require('./types')
+const Buffer = require('safe-buffer').Buffer
+const bech32 = require('bech32')
+const bs58check = require('bs58check')
+const bscript = require('./script')
+const btemplates = require('./templates')
+const networks = require('./networks')
+const typeforce = require('typeforce')
+const types = require('./types')
 
 function fromBase58Check (address) {
   var payload = bs58check.decode(address)
diff --git a/src/block.js b/src/block.js
index c545996..0d4a585 100644
--- a/src/block.js
+++ b/src/block.js
@@ -1,11 +1,11 @@
-var Buffer = require('safe-buffer').Buffer
-var bcrypto = require('./crypto')
-var fastMerkleRoot = require('merkle-lib/fastRoot')
-var typeforce = require('typeforce')
-var types = require('./types')
-var varuint = require('varuint-bitcoin')
+const Buffer = require('safe-buffer').Buffer
+const bcrypto = require('./crypto')
+const fastMerkleRoot = require('merkle-lib/fastRoot')
+const typeforce = require('typeforce')
+const types = require('./types')
+const varuint = require('varuint-bitcoin')
 
-var Transaction = require('./transaction')
+const Transaction = require('./transaction')
 
 function Block () {
   this.version = 1
diff --git a/src/crypto.js b/src/crypto.js
index 1bb39f1..a11d061 100644
--- a/src/crypto.js
+++ b/src/crypto.js
@@ -1,4 +1,4 @@
-var createHash = require('create-hash')
+const createHash = require('create-hash')
 
 function ripemd160 (buffer) {
   return createHash('rmd160').update(buffer).digest()
diff --git a/src/script.js b/src/script.js
index 612ce9d..63bf75d 100644
--- a/src/script.js
+++ b/src/script.js
@@ -1,14 +1,14 @@
-var Buffer = require('safe-buffer').Buffer
-var bip66 = require('bip66')
+const Buffer = require('safe-buffer').Buffer
+const bip66 = require('bip66')
 const ecc = require('tiny-secp256k1')
-var pushdata = require('pushdata-bitcoin')
-var typeforce = require('typeforce')
-var types = require('./types')
-var scriptNumber = require('./script_number')
+const pushdata = require('pushdata-bitcoin')
+const typeforce = require('typeforce')
+const types = require('./types')
+const scriptNumber = require('./script_number')
 
-var OPS = require('bitcoin-ops')
-var REVERSE_OPS = require('bitcoin-ops/map')
-var OP_INT_BASE = OPS.OP_RESERVED // OP_1 - 1
+const OPS = require('bitcoin-ops')
+const REVERSE_OPS = require('bitcoin-ops/map')
+const OP_INT_BASE = OPS.OP_RESERVED // OP_1 - 1
 
 function isOPInt (value) {
   return types.Number(value) &&
diff --git a/src/script_number.js b/src/script_number.js
index 3fd6326..6257690 100644
--- a/src/script_number.js
+++ b/src/script_number.js
@@ -1,4 +1,4 @@
-var Buffer = require('safe-buffer').Buffer
+const Buffer = require('safe-buffer').Buffer
 
 function decode (buffer, maxLength, minimal) {
   maxLength = maxLength || 4
diff --git a/src/templates/index.js b/src/templates/index.js
index af09112..4d7ce69 100644
--- a/src/templates/index.js
+++ b/src/templates/index.js
@@ -1,14 +1,14 @@
-var decompile = require('../script').decompile
-var multisig = require('./multisig')
-var nullData = require('./nulldata')
-var pubKey = require('./pubkey')
-var pubKeyHash = require('./pubkeyhash')
-var scriptHash = require('./scripthash')
-var witnessPubKeyHash = require('./witnesspubkeyhash')
-var witnessScriptHash = require('./witnessscripthash')
-var witnessCommitment = require('./witnesscommitment')
+const decompile = require('../script').decompile
+const multisig = require('./multisig')
+const nullData = require('./nulldata')
+const pubKey = require('./pubkey')
+const pubKeyHash = require('./pubkeyhash')
+const scriptHash = require('./scripthash')
+const witnessPubKeyHash = require('./witnesspubkeyhash')
+const witnessScriptHash = require('./witnessscripthash')
+const witnessCommitment = require('./witnesscommitment')
 
-var types = {
+const types = {
   MULTISIG: 'multisig',
   NONSTANDARD: 'nonstandard',
   NULLDATA: 'nulldata',
diff --git a/src/templates/multisig/input.js b/src/templates/multisig/input.js
index 0ba0a06..54f2a9f 100644
--- a/src/templates/multisig/input.js
+++ b/src/templates/multisig/input.js
@@ -1,10 +1,10 @@
 // OP_0 [signatures ...]
 
-var Buffer = require('safe-buffer').Buffer
-var bscript = require('../../script')
-var p2mso = require('./output')
-var typeforce = require('typeforce')
-var OPS = require('bitcoin-ops')
+const Buffer = require('safe-buffer').Buffer
+const bscript = require('../../script')
+const p2mso = require('./output')
+const typeforce = require('typeforce')
+const OPS = require('bitcoin-ops')
 
 function partialSignature (value) {
   return value === OPS.OP_0 || bscript.isCanonicalScriptSignature(value)
@@ -23,7 +23,7 @@ function check (script, allowIncomplete) {
 }
 check.toJSON = function () { return 'multisig input' }
 
-var EMPTY_BUFFER = Buffer.allocUnsafe(0)
+const EMPTY_BUFFER = Buffer.allocUnsafe(0)
 
 function encodeStack (signatures, scriptPubKey) {
   typeforce([partialSignature], signatures)
diff --git a/src/templates/multisig/output.js b/src/templates/multisig/output.js
index 70e8488..baef7e7 100644
--- a/src/templates/multisig/output.js
+++ b/src/templates/multisig/output.js
@@ -1,10 +1,10 @@
 // m [pubKeys ...] n OP_CHECKMULTISIG
 
-var bscript = require('../../script')
-var types = require('../../types')
-var typeforce = require('typeforce')
-var OPS = require('bitcoin-ops')
-var OP_INT_BASE = OPS.OP_RESERVED // OP_1 - 1
+const bscript = require('../../script')
+const types = require('../../types')
+const typeforce = require('typeforce')
+const OPS = require('bitcoin-ops')
+const OP_INT_BASE = OPS.OP_RESERVED // OP_1 - 1
 
 function check (script, allowIncomplete) {
   var chunks = bscript.decompile(script)
diff --git a/src/templates/nulldata.js b/src/templates/nulldata.js
index b7d53f8..1b9c404 100644
--- a/src/templates/nulldata.js
+++ b/src/templates/nulldata.js
@@ -1,9 +1,9 @@
 // OP_RETURN {data}
 
-var bscript = require('../script')
-var types = require('../types')
-var typeforce = require('typeforce')
-var OPS = require('bitcoin-ops')
+const bscript = require('../script')
+const types = require('../types')
+const typeforce = require('typeforce')
+const OPS = require('bitcoin-ops')
 
 function check (script) {
   var buffer = bscript.compile(script)
diff --git a/src/templates/pubkey/input.js b/src/templates/pubkey/input.js
index 9149289..e4cb931 100644
--- a/src/templates/pubkey/input.js
+++ b/src/templates/pubkey/input.js
@@ -1,7 +1,7 @@
 // {signature}
 
-var bscript = require('../../script')
-var typeforce = require('typeforce')
+const bscript = require('../../script')
+const typeforce = require('typeforce')
 
 function check (script) {
   var chunks = bscript.decompile(script)
diff --git a/src/templates/pubkey/output.js b/src/templates/pubkey/output.js
index 69a747f..f8bff2f 100644
--- a/src/templates/pubkey/output.js
+++ b/src/templates/pubkey/output.js
@@ -1,8 +1,8 @@
 // {pubKey} OP_CHECKSIG
 
-var bscript = require('../../script')
-var typeforce = require('typeforce')
-var OPS = require('bitcoin-ops')
+const bscript = require('../../script')
+const typeforce = require('typeforce')
+const OPS = require('bitcoin-ops')
 
 function check (script) {
   var chunks = bscript.decompile(script)
diff --git a/src/templates/pubkeyhash/input.js b/src/templates/pubkeyhash/input.js
index 81e1f80..0d5497b 100644
--- a/src/templates/pubkeyhash/input.js
+++ b/src/templates/pubkeyhash/input.js
@@ -1,7 +1,7 @@
 // {signature} {pubKey}
 
-var bscript = require('../../script')
-var typeforce = require('typeforce')
+const bscript = require('../../script')
+const typeforce = require('typeforce')
 
 function check (script) {
   var chunks = bscript.decompile(script)
diff --git a/src/templates/pubkeyhash/output.js b/src/templates/pubkeyhash/output.js
index 2a7c4ab..c89685b 100644
--- a/src/templates/pubkeyhash/output.js
+++ b/src/templates/pubkeyhash/output.js
@@ -1,9 +1,9 @@
 // OP_DUP OP_HASH160 {pubKeyHash} OP_EQUALVERIFY OP_CHECKSIG
 
-var bscript = require('../../script')
-var types = require('../../types')
-var typeforce = require('typeforce')
-var OPS = require('bitcoin-ops')
+const bscript = require('../../script')
+const types = require('../../types')
+const typeforce = require('typeforce')
+const OPS = require('bitcoin-ops')
 
 function check (script) {
   var buffer = bscript.compile(script)
diff --git a/src/templates/scripthash/input.js b/src/templates/scripthash/input.js
index 2ce55e3..a2d0693 100644
--- a/src/templates/scripthash/input.js
+++ b/src/templates/scripthash/input.js
@@ -1,14 +1,14 @@
 // <scriptSig> {serialized scriptPubKey script}
 
-var Buffer = require('safe-buffer').Buffer
-var bscript = require('../../script')
-var typeforce = require('typeforce')
+const Buffer = require('safe-buffer').Buffer
+const bscript = require('../../script')
+const typeforce = require('typeforce')
 
-var p2ms = require('../multisig/')
-var p2pk = require('../pubkey/')
-var p2pkh = require('../pubkeyhash/')
-var p2wpkho = require('../witnesspubkeyhash/output')
-var p2wsho = require('../witnessscripthash/output')
+const p2ms = require('../multisig/')
+const p2pk = require('../pubkey/')
+const p2pkh = require('../pubkeyhash/')
+const p2wpkho = require('../witnesspubkeyhash/output')
+const p2wsho = require('../witnessscripthash/output')
 
 function check (script, allowIncomplete) {
   var chunks = bscript.decompile(script)
diff --git a/src/templates/scripthash/output.js b/src/templates/scripthash/output.js
index 83d2501..d9776da 100644
--- a/src/templates/scripthash/output.js
+++ b/src/templates/scripthash/output.js
@@ -1,9 +1,9 @@
 // OP_HASH160 {scriptHash} OP_EQUAL
 
-var bscript = require('../../script')
-var types = require('../../types')
-var typeforce = require('typeforce')
-var OPS = require('bitcoin-ops')
+const bscript = require('../../script')
+const types = require('../../types')
+const typeforce = require('typeforce')
+const OPS = require('bitcoin-ops')
 
 function check (script) {
   var buffer = bscript.compile(script)
diff --git a/src/templates/witnesscommitment/output.js b/src/templates/witnesscommitment/output.js
index 3984ea5..5f97d69 100644
--- a/src/templates/witnesscommitment/output.js
+++ b/src/templates/witnesscommitment/output.js
@@ -1,12 +1,12 @@
 // OP_RETURN {aa21a9ed} {commitment}
 
-var Buffer = require('safe-buffer').Buffer
-var bscript = require('../../script')
-var types = require('../../types')
-var typeforce = require('typeforce')
-var OPS = require('bitcoin-ops')
+const Buffer = require('safe-buffer').Buffer
+const bscript = require('../../script')
+const types = require('../../types')
+const typeforce = require('typeforce')
+const OPS = require('bitcoin-ops')
 
-var HEADER = Buffer.from('aa21a9ed', 'hex')
+const HEADER = Buffer.from('aa21a9ed', 'hex')
 
 function check (script) {
   var buffer = bscript.compile(script)
diff --git a/src/templates/witnesspubkeyhash/input.js b/src/templates/witnesspubkeyhash/input.js
index 089c8d8..a0549ff 100644
--- a/src/templates/witnesspubkeyhash/input.js
+++ b/src/templates/witnesspubkeyhash/input.js
@@ -1,7 +1,7 @@
 // {signature} {pubKey}
 
-var bscript = require('../../script')
-var typeforce = require('typeforce')
+const bscript = require('../../script')
+const typeforce = require('typeforce')
 
 function isCompressedCanonicalPubKey (pubKey) {
   return bscript.isCanonicalPubKey(pubKey) && pubKey.length === 33
diff --git a/src/templates/witnesspubkeyhash/output.js b/src/templates/witnesspubkeyhash/output.js
index ebcb185..d2b091b 100644
--- a/src/templates/witnesspubkeyhash/output.js
+++ b/src/templates/witnesspubkeyhash/output.js
@@ -1,9 +1,9 @@
 // OP_0 {pubKeyHash}
 
-var bscript = require('../../script')
-var types = require('../../types')
-var typeforce = require('typeforce')
-var OPS = require('bitcoin-ops')
+const bscript = require('../../script')
+const types = require('../../types')
+const typeforce = require('typeforce')
+const OPS = require('bitcoin-ops')
 
 function check (script) {
   var buffer = bscript.compile(script)
diff --git a/src/templates/witnessscripthash/input.js b/src/templates/witnessscripthash/input.js
index d6e85f5..c21ee1e 100644
--- a/src/templates/witnessscripthash/input.js
+++ b/src/templates/witnessscripthash/input.js
@@ -1,12 +1,12 @@
 // <scriptSig> {serialized scriptPubKey script}
 
-var bscript = require('../../script')
-var types = require('../../types')
-var typeforce = require('typeforce')
+const bscript = require('../../script')
+const types = require('../../types')
+const typeforce = require('typeforce')
 
-var p2ms = require('../multisig/')
-var p2pk = require('../pubkey/')
-var p2pkh = require('../pubkeyhash/')
+const p2ms = require('../multisig/')
+const p2pk = require('../pubkey/')
+const p2pkh = require('../pubkeyhash/')
 
 function check (chunks, allowIncomplete) {
   typeforce(types.Array, chunks)
diff --git a/src/templates/witnessscripthash/output.js b/src/templates/witnessscripthash/output.js
index f1656b5..d800fda 100644
--- a/src/templates/witnessscripthash/output.js
+++ b/src/templates/witnessscripthash/output.js
@@ -1,9 +1,9 @@
 // OP_0 {scriptHash}
 
-var bscript = require('../../script')
-var types = require('../../types')
-var typeforce = require('typeforce')
-var OPS = require('bitcoin-ops')
+const bscript = require('../../script')
+const types = require('../../types')
+const typeforce = require('typeforce')
+const OPS = require('bitcoin-ops')
 
 function check (script) {
   var buffer = bscript.compile(script)
diff --git a/src/transaction.js b/src/transaction.js
index 86cccea..8187c73 100644
--- a/src/transaction.js
+++ b/src/transaction.js
@@ -1,11 +1,11 @@
-var Buffer = require('safe-buffer').Buffer
-var bcrypto = require('./crypto')
-var bscript = require('./script')
-var bufferutils = require('./bufferutils')
-var opcodes = require('bitcoin-ops')
-var typeforce = require('typeforce')
-var types = require('./types')
-var varuint = require('varuint-bitcoin')
+const Buffer = require('safe-buffer').Buffer
+const bcrypto = require('./crypto')
+const bscript = require('./script')
+const bufferutils = require('./bufferutils')
+const opcodes = require('bitcoin-ops')
+const typeforce = require('typeforce')
+const types = require('./types')
+const varuint = require('varuint-bitcoin')
 
 function varSliceSize (someScript) {
   var length = someScript.length
@@ -36,12 +36,12 @@ Transaction.SIGHASH_ANYONECANPAY = 0x80
 Transaction.ADVANCED_TRANSACTION_MARKER = 0x00
 Transaction.ADVANCED_TRANSACTION_FLAG = 0x01
 
-var EMPTY_SCRIPT = Buffer.allocUnsafe(0)
-var EMPTY_WITNESS = []
-var ZERO = Buffer.from('0000000000000000000000000000000000000000000000000000000000000000', 'hex')
-var ONE = Buffer.from('0000000000000000000000000000000000000000000000000000000000000001', 'hex')
-var VALUE_UINT64_MAX = Buffer.from('ffffffffffffffff', 'hex')
-var BLANK_OUTPUT = {
+const EMPTY_SCRIPT = Buffer.allocUnsafe(0)
+const EMPTY_WITNESS = []
+const ZERO = Buffer.from('0000000000000000000000000000000000000000000000000000000000000000', 'hex')
+const ONE = Buffer.from('0000000000000000000000000000000000000000000000000000000000000001', 'hex')
+const VALUE_UINT64_MAX = Buffer.from('ffffffffffffffff', 'hex')
+const BLANK_OUTPUT = {
   script: EMPTY_SCRIPT,
   valueBuffer: VALUE_UINT64_MAX
 }
diff --git a/src/transaction_builder.js b/src/transaction_builder.js
index 4f731dc..d5ad34c 100644
--- a/src/transaction_builder.js
+++ b/src/transaction_builder.js
@@ -1,18 +1,18 @@
-var Buffer = require('safe-buffer').Buffer
-var baddress = require('./address')
-var bcrypto = require('./crypto')
-var bscript = require('./script')
-var btemplates = require('./templates')
-var networks = require('./networks')
-var ops = require('bitcoin-ops')
-var typeforce = require('typeforce')
-var types = require('./types')
-var scriptTypes = btemplates.types
-var SIGNABLE = [btemplates.types.P2PKH, btemplates.types.P2PK, btemplates.types.MULTISIG]
-var P2SH = SIGNABLE.concat([btemplates.types.P2WPKH, btemplates.types.P2WSH])
+const Buffer = require('safe-buffer').Buffer
+const baddress = require('./address')
+const bcrypto = require('./crypto')
+const bscript = require('./script')
+const btemplates = require('./templates')
+const networks = require('./networks')
+const ops = require('bitcoin-ops')
+const typeforce = require('typeforce')
+const types = require('./types')
+const scriptTypes = btemplates.types
+const SIGNABLE = [btemplates.types.P2PKH, btemplates.types.P2PK, btemplates.types.MULTISIG]
+const P2SH = SIGNABLE.concat([btemplates.types.P2WPKH, btemplates.types.P2WSH])
 
-var ECPair = require('./ecpair')
-var Transaction = require('./transaction')
+const ECPair = require('./ecpair')
+const Transaction = require('./transaction')
 
 function supportedType (type) {
   return SIGNABLE.indexOf(type) !== -1
diff --git a/src/types.js b/src/types.js
index 302043f..2d1ec6f 100644
--- a/src/types.js
+++ b/src/types.js
@@ -1,6 +1,6 @@
-var typeforce = require('typeforce')
+const typeforce = require('typeforce')
 
-var UINT31_MAX = Math.pow(2, 31) - 1
+const UINT31_MAX = Math.pow(2, 31) - 1
 function UInt31 (value) {
   return typeforce.UInt32(value) && value <= UINT31_MAX
 }
@@ -10,16 +10,16 @@ function BIP32Path (value) {
 }
 BIP32Path.toJSON = function () { return 'BIP32 derivation path' }
 
-var SATOSHI_MAX = 21 * 1e14
+const SATOSHI_MAX = 21 * 1e14
 function Satoshi (value) {
   return typeforce.UInt53(value) && value <= SATOSHI_MAX
 }
 
 // external dependent types
-var ECPoint = typeforce.quacksLike('Point')
+const ECPoint = typeforce.quacksLike('Point')
 
 // exposed, external API
-var Network = typeforce.compile({
+const Network = typeforce.compile({
   messagePrefix: typeforce.oneOf(typeforce.Buffer, typeforce.String),
   bip32: {
     public: typeforce.UInt32,
@@ -31,7 +31,7 @@ var Network = typeforce.compile({
 })
 
 // extend typeforce types with ours
-var types = {
+const types = {
   BIP32Path: BIP32Path,
   Buffer256bit: typeforce.BufferN(32),
   ECPoint: ECPoint,
diff --git a/test/bitcoin.core.js b/test/bitcoin.core.js
index 4d73c2a..bda6899 100644
--- a/test/bitcoin.core.js
+++ b/test/bitcoin.core.js
@@ -1,17 +1,17 @@
 /* global describe, it */
 
-var assert = require('assert')
-var base58 = require('bs58')
-var bitcoin = require('../')
+const assert = require('assert')
+const base58 = require('bs58')
+const bitcoin = require('../')
 
-var base58EncodeDecode = require('./fixtures/core/base58_encode_decode.json')
-var base58KeysInvalid = require('./fixtures/core/base58_keys_invalid.json')
-var base58KeysValid = require('./fixtures/core/base58_keys_valid.json')
-var blocksValid = require('./fixtures/core/blocks.json')
-var sigCanonical = require('./fixtures/core/sig_canonical.json')
-var sigHash = require('./fixtures/core/sighash.json')
-var sigNoncanonical = require('./fixtures/core/sig_noncanonical.json')
-var txValid = require('./fixtures/core/tx_valid.json')
+const base58EncodeDecode = require('./fixtures/core/base58_encode_decode.json')
+const base58KeysInvalid = require('./fixtures/core/base58_keys_invalid.json')
+const base58KeysValid = require('./fixtures/core/base58_keys_valid.json')
+const blocksValid = require('./fixtures/core/blocks.json')
+const sigCanonical = require('./fixtures/core/sig_canonical.json')
+const sigHash = require('./fixtures/core/sighash.json')
+const sigNoncanonical = require('./fixtures/core/sig_noncanonical.json')
+const txValid = require('./fixtures/core/tx_valid.json')
 
 describe('Bitcoin-core', function () {
   // base58EncodeDecode
diff --git a/test/block.js b/test/block.js
index 19866e5..5794d66 100644
--- a/test/block.js
+++ b/test/block.js
@@ -1,9 +1,9 @@
 /* global describe, it, beforeEach */
 
-var assert = require('assert')
-var Block = require('../src/block')
+const assert = require('assert')
+const Block = require('../src/block')
 
-var fixtures = require('./fixtures/block')
+const fixtures = require('./fixtures/block')
 
 describe('Block', function () {
   describe('version', function () {
diff --git a/test/bufferutils.js b/test/bufferutils.js
index e172ba1..da98828 100644
--- a/test/bufferutils.js
+++ b/test/bufferutils.js
@@ -1,9 +1,9 @@
 /* global describe, it */
 
-var assert = require('assert')
-var bufferutils = require('../src/bufferutils')
+const assert = require('assert')
+const bufferutils = require('../src/bufferutils')
 
-var fixtures = require('./fixtures/bufferutils.json')
+const fixtures = require('./fixtures/bufferutils.json')
 
 describe('bufferutils', function () {
   describe('readUInt64LE', function () {
diff --git a/test/crypto.js b/test/crypto.js
index 0fcc24b..91bc674 100644
--- a/test/crypto.js
+++ b/test/crypto.js
@@ -1,9 +1,9 @@
 /* global describe, it */
 
-var assert = require('assert')
-var bcrypto = require('../src/crypto')
+const assert = require('assert')
+const bcrypto = require('../src/crypto')
 
-var fixtures = require('./fixtures/crypto')
+const fixtures = require('./fixtures/crypto')
 
 describe('crypto', function () {
   ['hash160', 'hash256', 'ripemd160', 'sha1', 'sha256'].forEach(function (algorithm) {
diff --git a/test/integration/_regtest.js b/test/integration/_regtest.js
index 409f908..91b25d5 100644
--- a/test/integration/_regtest.js
+++ b/test/integration/_regtest.js
@@ -1,9 +1,9 @@
-var assert = require('assert')
-var bitcoin = require('../../')
-var dhttp = require('dhttp/200')
+const assert = require('assert')
+const bitcoin = require('../../')
+const dhttp = require('dhttp/200')
 
-var APIPASS = process.env.APIPASS || 'satoshi'
-var APIURL = 'https://api.dcousens.cloud/1'
+const APIPASS = process.env.APIPASS || 'satoshi'
+const APIURL = 'https://api.dcousens.cloud/1'
 
 function broadcast (txHex, callback) {
   dhttp({
diff --git a/test/integration/blocks.js b/test/integration/blocks.js
index 56eca68..d4a7ec4 100644
--- a/test/integration/blocks.js
+++ b/test/integration/blocks.js
@@ -1,8 +1,8 @@
 /* global describe, it */
 'use strict'
 
-var assert = require('assert')
-var bitcoin = require('../../')
+const assert = require('assert')
+const bitcoin = require('../../')
 
 describe('bitcoinjs-lib (blocks)', function () {
   it('can extract a height from a CoinBase transaction', function () {
diff --git a/test/integration/cltv.js b/test/integration/cltv.js
index b7c6c2c..90e78a9 100644
--- a/test/integration/cltv.js
+++ b/test/integration/cltv.js
@@ -1,13 +1,13 @@
 /* global describe, it, before */
 
-var assert = require('assert')
-var bitcoin = require('../../')
-var regtestUtils = require('./_regtest')
-var regtest = regtestUtils.network
-var bip65 = require('bip65')
+const assert = require('assert')
+const bitcoin = require('../../')
+const regtestUtils = require('./_regtest')
+const regtest = regtestUtils.network
+const bip65 = require('bip65')
 
-var alice = bitcoin.ECPair.fromWIF('cScfkGjbzzoeewVWmU2hYPUHeVGJRDdFt7WhmrVVGkxpmPP8BHWe', regtest)
-var bob = bitcoin.ECPair.fromWIF('cMkopUXKWsEzAjfa1zApksGRwjVpJRB3831qM9W4gKZsLwjHXA9x', regtest)
+const alice = bitcoin.ECPair.fromWIF('cScfkGjbzzoeewVWmU2hYPUHeVGJRDdFt7WhmrVVGkxpmPP8BHWe', regtest)
+const bob = bitcoin.ECPair.fromWIF('cMkopUXKWsEzAjfa1zApksGRwjVpJRB3831qM9W4gKZsLwjHXA9x', regtest)
 
 describe('bitcoinjs-lib (transactions w/ CLTV)', function () {
   // force update MTP
diff --git a/test/integration/crypto.js b/test/integration/crypto.js
index 58ae431..deddf67 100644
--- a/test/integration/crypto.js
+++ b/test/integration/crypto.js
@@ -1,14 +1,14 @@
 /* global describe, it */
 
-var assert = require('assert')
-var bigi = require('bigi')
-var bitcoin = require('../../')
-var bip32 = require('bip32')
-var crypto = require('crypto')
-var tinysecp = require('tiny-secp256k1')
+const assert = require('assert')
+const bigi = require('bigi')
+const bitcoin = require('../../')
+const bip32 = require('bip32')
+const crypto = require('crypto')
+const tinysecp = require('tiny-secp256k1')
 
-var ecurve = require('ecurve')
-var secp256k1 = ecurve.getCurveByName('secp256k1')
+const ecurve = require('ecurve')
+const secp256k1 = ecurve.getCurveByName('secp256k1')
 
 describe('bitcoinjs-lib (crypto)', function () {
   it('can recover a private key from duplicate R values', function () {
diff --git a/test/script.js b/test/script.js
index 537e75a..71c9d72 100644
--- a/test/script.js
+++ b/test/script.js
@@ -1,11 +1,11 @@
 /* global describe, it */
 
-var assert = require('assert')
-var bscript = require('../src/script')
-var minimalData = require('minimaldata')
+const assert = require('assert')
+const bscript = require('../src/script')
+const minimalData = require('minimaldata')
 
-var fixtures = require('./fixtures/script.json')
-var fixtures2 = require('./fixtures/templates.json')
+const fixtures = require('./fixtures/script.json')
+const fixtures2 = require('./fixtures/templates.json')
 
 describe('script', function () {
   // TODO
diff --git a/test/script_number.js b/test/script_number.js
index 2aa33a7..9eb0820 100644
--- a/test/script_number.js
+++ b/test/script_number.js
@@ -1,8 +1,8 @@
 /* global describe, it */
 
-var assert = require('assert')
-var scriptNumber = require('../src/script_number')
-var fixtures = require('./fixtures/script_number.json')
+const assert = require('assert')
+const scriptNumber = require('../src/script_number')
+const fixtures = require('./fixtures/script_number.json')
 
 describe('script-number', function () {
   describe('decode', function () {
diff --git a/test/script_signature.js b/test/script_signature.js
index f53bc52..2c22540 100644
--- a/test/script_signature.js
+++ b/test/script_signature.js
@@ -1,9 +1,9 @@
 /* global describe, it */
 
-var assert = require('assert')
-var bscriptSig = require('../src/script').signature
-var Buffer = require('safe-buffer').Buffer
-var fixtures = require('./fixtures/signature.json')
+const assert = require('assert')
+const bscriptSig = require('../src/script').signature
+const Buffer = require('safe-buffer').Buffer
+const fixtures = require('./fixtures/signature.json')
 
 describe('Script Signatures', function () {
   function fromRaw (signature) {
diff --git a/test/templates.js b/test/templates.js
index c89bd52..a850564 100644
--- a/test/templates.js
+++ b/test/templates.js
@@ -1,12 +1,12 @@
 /* global describe, it */
 
-var assert = require('assert')
-var bcrypto = require('../src/crypto')
-var bscript = require('../src/script')
-var btemplates = require('../src/templates')
-var ops = require('bitcoin-ops')
+const assert = require('assert')
+const bcrypto = require('../src/crypto')
+const bscript = require('../src/script')
+const btemplates = require('../src/templates')
+const ops = require('bitcoin-ops')
 
-var fixtures = require('./fixtures/templates.json')
+const fixtures = require('./fixtures/templates.json')
 
 function fromHex (x) { return Buffer.from(x, 'hex') }
 function toHex (x) { return x.toString('hex') }
diff --git a/test/transaction.js b/test/transaction.js
index 62c24d0..fa69640 100644
--- a/test/transaction.js
+++ b/test/transaction.js
@@ -1,9 +1,9 @@
 /* global describe, it, beforeEach */
 
-var assert = require('assert')
-var bscript = require('../src/script')
-var fixtures = require('./fixtures/transaction')
-var Transaction = require('../src/transaction')
+const assert = require('assert')
+const bscript = require('../src/script')
+const fixtures = require('./fixtures/transaction')
+const Transaction = require('../src/transaction')
 
 describe('Transaction', function () {
   function fromRaw (raw, noWitness) {
diff --git a/test/types.js b/test/types.js
index 2dbc554..ab2110d 100644
--- a/test/types.js
+++ b/test/types.js
@@ -1,8 +1,8 @@
 /* global describe, it */
 
-var assert = require('assert')
-var types = require('../src/types')
-var typeforce = require('typeforce')
+const assert = require('assert')
+const types = require('../src/types')
+const typeforce = require('typeforce')
 
 describe('types', function () {
   describe('Buffer Hash160/Hash256', function () {