diff --git a/lib/boleto.js b/lib/boleto.js
index 5eb2b53..966398c 100644
--- a/lib/boleto.js
+++ b/lib/boleto.js
@@ -4,54 +4,66 @@ const barcode = require('./barcode')
 const path = require('path')
 const moment = require('moment')
 
-var banks = null
+let banks = null
 
-var hashString = function (string) {
-  var hash = 0
-  var i
-  var chr
-  var len
+const hashString = function (string) {
+  let hash = 0
+  let i
+  let chr
+  let len
 
-  if (string.length == 0) return hash
+  if (string.length === 0) return hash
   for (i = 0, len = string.length; i < len; i++) {
     chr = string.charCodeAt(i)
-    hash = ((hash << 5) - hash) + chr
+    hash = (hash << 5) - hash + chr
     hash |= 0 // Convert to 32bit integer
   }
   return hash
 }
 
-var Boleto = function (options) {
+const Boleto = function (options) {
   if (!options) {
     throw 'No options provided initializing Boleto.'
   }
 
-  this.bank = banks[options['banco']]
+  this.bank = banks[ options[ 'banco' ] ]
   if (!this.bank) {
     throw 'Invalid bank.'
   }
 
-  if (!options['data_emissao']) {
-    options['data_emissao'] = moment().utc()
+  if (!options[ 'data_emissao' ]) {
+    options[ 'data_emissao' ] = moment().utc()
   } else {
-    options['data_emissao'] = moment(moment(options['data_emissao']).utc().format('YYYY-MM-DD'))
+    options[ 'data_emissao' ] = moment(
+      moment(options[ 'data_emissao' ])
+        .utc()
+        .format('YYYY-MM-DD')
+    )
   }
 
-  if (!options['data_vencimento']) {
-    options['data_vencimento'] = moment().utc().add('5', 'days')
+  if (!options[ 'data_vencimento' ]) {
+    options[ 'data_vencimento' ] = moment()
+      .utc()
+      .add('5', 'days')
   } else {
-    options['data_vencimento'] = moment(moment(options['data_vencimento']).utc().format('YYYY-MM-DD'))
+    options[ 'data_vencimento' ] = moment(
+      moment(options[ 'data_vencimento' ])
+        .utc()
+        .format('YYYY-MM-DD')
+    )
   }
 
-  for (var key in options) {
-    this[key] = options[key]
+  for (let key in options) {
+    this[ key ] = options[ key ]
   }
 
-  this['pagador'] = formatters.htmlString(this['pagador'])
-  this['instrucoes'] = formatters.htmlString(this['instrucoes'])
+  this[ 'pagador' ] = formatters.htmlString(this[ 'pagador' ])
+  this[ 'instrucoes' ] = formatters.htmlString(this[ 'instrucoes' ])
 
-  if (!this['local_de_pagamento']) {
-    this['local_de_pagamento'] = 'Até o vencimento, preferencialmente no Banco ' + formatters.capitalize(this['banco'])
+  if (!this[ 'local_de_pagamento' ]) {
+    this[ 'local_de_pagamento' ] =
+      'Até o vencimento, preferencialmente no Banco ' +
+      formatters.capitalize(this[ 'banco' ])
   }
 
   this._calculate()
@@ -60,43 +72,55 @@ var Boleto = function (options) {
 Boleto.barcodeRenderEngine = 'img'
 
 Boleto.prototype._calculate = function () {
-  this['codigo_banco'] = this.bank.options.codigo + '-' + formatters.mod11(this.bank.options.codigo)
-  this['nosso_numero_dv'] = formatters.mod11(this['nosso_numero'].toString())
-  this['barcode_data'] = this.bank.barcodeData(this)
-  this['linha_digitavel'] = this.bank.linhaDigitavel(this['barcode_data'])
+  this[ 'codigo_banco' ] =
+    this.bank.options.codigo + '-' + formatters.mod11(this.bank.options.codigo)
+  this[ 'nosso_numero_dv' ] = formatters.mod11(this[ 'nosso_numero' ].toString())
+  this[ 'barcode_data' ] = this.bank.barcodeData(this)
+  this[ 'linha_digitavel' ] = this.bank.linhaDigitavel(this[ 'barcode_data' ])
 }
 
 Boleto.prototype.renderHTML = function (callback) {
-  var self = this
+  const self = this
 
-  var renderOptions = self.bank.options
+  let renderOptions = self.bank.options
   renderOptions.boleto = self
 
   // Copy renderHelper's methods to renderOptions
-  for (var key in formatters) {
-    renderOptions[key] = formatters[key]
+  for (let key in formatters) {
+    renderOptions[ key ] = formatters[ key ]
   }
 
-  renderOptions['barcode_render_engine'] = Boleto.barcodeRenderEngine
-  renderOptions['barcode_height'] = '50'
-
-  if (Boleto.barcodeRenderEngine == 'bmp') {
-    renderOptions['barcode_data'] = barcode.bmpLineForBarcodeData(self['barcode_data'])
-  } else if (Boleto.barcodeRenderEngine == 'img') {
-    renderOptions['barcode_data'] = barcode.binaryRepresentationForBarcodeData(self['barcode_data'])
+  renderOptions[ 'barcode_render_engine' ] = Boleto.barcodeRenderEngine
+  renderOptions[ 'barcode_height' ] = '50'
+
+  if (Boleto.barcodeRenderEngine === 'bmp') {
+    renderOptions[ 'barcode_data' ] = barcode.bmpLineForBarcodeData(
+      self[ 'barcode_data' ]
+    )
+  } else if (Boleto.barcodeRenderEngine === 'img') {
+    renderOptions[ 'barcode_data' ] = barcode.binaryRepresentationForBarcodeData(
+      self[ 'barcode_data' ]
+    )
   }
 
-  renderOptions['boleto']['linha_digitavel_hash'] = hashString(renderOptions['boleto']['linha_digitavel']).toString()
-
-  ejs.renderFile(path.join(__dirname, '/../assets/layout.ejs'), renderOptions, {
-    cache: true
-  }, function (err, html) {
-    if (err) {
-      throw new Error(err)
+  renderOptions[ 'boleto' ][ 'linha_digitavel_hash' ] = hashString(
+    renderOptions[ 'boleto' ][ 'linha_digitavel' ]
+  ).toString()
+
+  ejs.renderFile(
+    path.join(__dirname, '/../assets/layout.ejs'),
+    renderOptions,
+    {
+      cache: true
+    },
+    function (err, html) {
+      if (err) {
+        throw new Error(err)
+      }
+
+      callback(html)
     }
-
-    callback(html)
-  })
+  )
 }
 
 module.exports = function (_banks) {
diff --git a/lib/edi-helper.js b/lib/edi-helper.js
index 991cf1d..947df2e 100644
--- a/lib/edi-helper.js
+++ b/lib/edi-helper.js
@@ -1,6 +1,8 @@
-var crypto = require('crypto')
+const crypto = require('crypto')
 
 exports.calculateLineChecksum = function (line) {
-  return crypto.createHash('sha1').update(line).digest('hex')
+  return crypto
+    .createHash('sha1')
+    .update(line)
+    .digest('hex')
 }
-
diff --git a/lib/formatters.js b/lib/formatters.js
index 62286a9..1c38c3e 100644
--- a/lib/formatters.js
+++ b/lib/formatters.js
@@ -17,14 +17,20 @@ exports.addTrailingZeros = function (string, length) {
 
 exports.formatAmount = function (amount) {
   amount = amount.toString()
-  var cents = exports.addTrailingZeros(amount.substring(amount.length - 2, amount.length), 2)
-  var integers = exports.addTrailingZeros(amount.substring(0, amount.length - 2), 1)
-
-  var newIntegers = ''
-
-  for (var i = 0; i < integers.length; i++) {
-    if (i > 0 && (integers.length - i) % 3 == 0) newIntegers += '.'
-    newIntegers += integers[i]
+  const cents = exports.addTrailingZeros(
+    amount.substring(amount.length - 2, amount.length),
+    2
+  )
+  const integers = exports.addTrailingZeros(
+    amount.substring(0, amount.length - 2),
+    1
+  )
+
+  let newIntegers = ''
+
+  for (let i = 0; i < integers.length; i++) {
+    if (i > 0 && (integers.length - i) % 3 === 0) newIntegers += '.'
+    newIntegers += integers[ i ]
   }
 
   return 'R$ ' + newIntegers + ',' + cents
@@ -38,59 +44,67 @@ exports.mod11 = function (num, base, r) {
   if (!base) base = 9
   if (!r) r = 0
 
-  var soma = 0
-  var fator = 2
+  let soma = 0
+  let fator = 2
 
-  for (var i = num.length - 1; i >= 0; i--) {
-    var parcial = parseInt(num[i]) * fator
+  for (let i = num.length - 1; i >= 0; i--) {
+    const parcial = parseInt(num[ i ]) * fator
     soma += parcial
 
-    if (fator == base) {
+    if (fator === base) {
       fator = 1
     }
 
     fator++
   }
 
-  if (r == 0) {
+  if (r === 0) {
     soma *= 10
-    var digito = soma % 11
-    return digito == 10 ? 0 : digito
-  } else if (r == 1) {
+    const digito = soma % 11
+    return digito === 10 ? 0 : digito
+  } else if (r === 1) {
     return soma % 11
   }
 }
 
 exports.mod10 = function (num) {
-  var total = 0
-  var fator = 2
-
-  for (var i = num.length - 1; i >= 0; i--) {
-    var temp = (parseInt(num[i]) * fator).toString()
-    var tempSum = 0
-    for (var j = 0; j < temp.length; j++) {
-      tempSum += parseInt(temp[j])
+  let total = 0
+  let fator = 2
+
+  for (let i = num.length - 1; i >= 0; i--) {
+    const temp = (parseInt(num[ i ]) * fator).toString()
+    let tempSum = 0
+    for (let j = 0; j < temp.length; j++) {
+      tempSum += parseInt(temp[ j ])
     }
     total += tempSum
-    fator = (fator == 2) ? 1 : 2
+    fator = fator === 2 ? 1 : 2
   }
 
-  var resto = total % 10
-  return (resto == 0) ? 0 : (10 - resto)
+  const resto = total % 10
+  return resto === 0 ? 0 : 10 - resto
 }
 
 exports.fatorVencimento = function (date) {
-  const parsedDate = moment(date).utc().format('YYYY-MM-DD')
-  const startDate = moment('1997-10-07').utc().format('YYYY-MM-DD')
+  const parsedDate = moment(date)
+    .utc()
+    .format('YYYY-MM-DD')
+  const startDate = moment('1997-10-07')
+    .utc()
+    .format('YYYY-MM-DD')
   return exports.addTrailingZeros(moment(parsedDate).diff(startDate, 'days'), 4)
 }
 
 exports.dateFromEdiDate = function (ediDate) {
-  return new Date(parseInt(ediDate.substring(4, 8)), parseInt(ediDate.substring(2, 4)) - 1, parseInt(ediDate.substring(0, 2)))
+  return new Date(
+    parseInt(ediDate.substring(4, 8)),
+    parseInt(ediDate.substring(2, 4)) - 1,
+    parseInt(ediDate.substring(0, 2))
+  )
 }
 
 exports.removeTrailingZeros = function (string) {
-  while (string.charAt(0) == '0') {
+  while (string.charAt(0) === '0') {
     string = string.substring(1, string.length)
   }