diff --git a/index.js b/index.js
index 4240cab1c9..6002cb0763 100644
--- a/index.js
+++ b/index.js
@@ -296,7 +296,7 @@ RedisClient.prototype.warn = function (msg) {
 RedisClient.prototype.flushAndError = function (errorAttributes, options) {
   options = options || {}
   const queueNames = options.queues || ['commandQueue', 'offlineQueue'] // Flush the commandQueue first to keep the order intact
-  for (let i = 0; i < queueNames.length; i++) {
+  for (var i = 0; i < queueNames.length; i++) {
     // If the command was fired it might have been processed so far
     if (queueNames[i] === 'commandQueue') {
       errorAttributes.message += ' It might have been processed.'
@@ -304,7 +304,7 @@ RedisClient.prototype.flushAndError = function (errorAttributes, options) {
       errorAttributes.message = errorAttributes.message.replace(' It might have been processed.', '')
     }
     // Don't flush everything from the queue
-    for (let commandObj = this[queueNames[i]].shift(); commandObj; commandObj = this[queueNames[i]].shift()) {
+    for (var commandObj = this[queueNames[i]].shift(); commandObj; commandObj = this[queueNames[i]].shift()) {
       const err = new errorClasses.AbortError(errorAttributes)
       if (commandObj.error) {
         err.stack = err.stack + commandObj.error.stack.replace(/^Error.*?\n/, '\n')
@@ -456,7 +456,7 @@ RedisClient.prototype.onInfoCmd = function (res) {
     }
   }
 
-  let retryTime = +this.serverInfo.loading_eta_seconds * 1000
+  var retryTime = +this.serverInfo.loading_eta_seconds * 1000
   if (retryTime > 1000) {
     retryTime = 1000
   }
@@ -477,7 +477,7 @@ RedisClient.prototype.readyCheck = function () {
 }
 
 RedisClient.prototype.sendOfflineQueue = function () {
-  for (let commandObj = this.offlineQueue.shift(); commandObj; commandObj = this.offlineQueue.shift()) {
+  for (var commandObj = this.offlineQueue.shift(); commandObj; commandObj = this.offlineQueue.shift()) {
     debug('Sending offline command: %s', commandObj.command)
     this.internalSendCommand(commandObj)
   }
@@ -648,8 +648,8 @@ function subscribeUnsubscribe (self, reply, type) {
 
   if (commandObj.argsLength === 1 || self.subCommandsLeft === 1 || commandObj.argsLength === 0 && (count === 0 || channel === null)) {
     if (count === 0) { // unsubscribed from all channels
-      let runningCommand
-      let i = 1
+      var runningCommand
+      var i = 1
       self.pubSubMode = 0 // Deactivating pub sub mode
       // This should be a rare case and therefore handling it this way should be good performance wise for the general case
       for (runningCommand = self.commandQueue.get(i); runningCommand !== undefined; runningCommand = self.commandQueue.get(i)) {
@@ -699,7 +699,7 @@ RedisClient.prototype.returnReply = function (reply) {
   // As this is not the average use case and monitor is expensive anyway, let's change the code here, to improve
   // the average performance of all other commands in case of no monitor mode
   if (this.monitoring) {
-    let replyStr
+    var replyStr
     if (this.buffers && Buffer.isBuffer(reply)) {
       replyStr = reply.toString()
     } else {
@@ -731,8 +731,8 @@ RedisClient.prototype.returnReply = function (reply) {
 }
 
 function handleOfflineCommand (self, commandObj) {
-  let command = commandObj.command
-  let err, msg
+  var command = commandObj.command
+  var err, msg
   if (self.closing || !self.enableOfflineQueue) {
     command = command.toUpperCase()
     if (!self.closing) {
@@ -793,8 +793,8 @@ RedisClient.prototype.internalSendCommand = function (commandObj) {
 }
 
 RedisClient.prototype.writeStrings = function () {
-  let str = ''
-  for (let command = this.pipelineQueue.shift(); command; command = this.pipelineQueue.shift()) {
+  var str = ''
+  for (var command = this.pipelineQueue.shift(); command; command = this.pipelineQueue.shift()) {
     // Write to stream if the string is bigger than 4mb. The biggest string may be Math.pow(2, 28) - 15 chars long
     if (str.length + command.length > 4 * 1024 * 1024) {
       this.shouldBuffer = !this.stream.write(str)
@@ -808,7 +808,7 @@ RedisClient.prototype.writeStrings = function () {
 }
 
 RedisClient.prototype.writeBuffers = function () {
-  for (let command = this.pipelineQueue.shift(); command; command = this.pipelineQueue.shift()) {
+  for (var command = this.pipelineQueue.shift(); command; command = this.pipelineQueue.shift()) {
     this.shouldBuffer = !this.stream.write(command)
   }
 }
diff --git a/lib/customErrors.js b/lib/customErrors.js
index 43583fb867..f40f09facb 100644
--- a/lib/customErrors.js
+++ b/lib/customErrors.js
@@ -16,7 +16,7 @@ class AbortError extends RedisError {
     if (stack || stack === undefined) {
       Error.captureStackTrace(this, AbortError)
     }
-    for (let keys = Object.keys(obj), key = keys.pop(); key; key = keys.pop()) {
+    for (var keys = Object.keys(obj), key = keys.pop(); key; key = keys.pop()) {
       this[key] = obj[key]
     }
   }
diff --git a/lib/individualCommands.js b/lib/individualCommands.js
index 7447e7d2bd..2d96f3fa57 100644
--- a/lib/individualCommands.js
+++ b/lib/individualCommands.js
@@ -117,7 +117,7 @@ function infoCallback (self) {
     const lines = res.toString().split('\r\n')
     var line, parts, subParts
 
-    for (let i = 0; i < lines.length; i++) {
+    for (var i = 0; i < lines.length; i++) {
       parts = lines[i].split(':')
       if (parts[1]) {
         if (parts[0].indexOf('db') === 0) {
diff --git a/lib/multi.js b/lib/multi.js
index c10be736bc..b7a1272f0b 100644
--- a/lib/multi.js
+++ b/lib/multi.js
@@ -90,7 +90,7 @@ function execTransaction (multi) {
   // Silently ignore this error. We'll receive the error for the exec as well
   const promises = [multi._client.internalSendCommand(new Command('multi', [])).catch(() => {})]
   // Drain queue, callback will catch 'QUEUED' or error
-  for (let index = 0; index < len; index++) {
+  for (var index = 0; index < len; index++) {
     // The commands may not be shifted off, since they are needed in the result handler
     promises.push(pipelineTransactionCommand(multi, multi._queue.get(index), index).catch((e) => e))
   }
@@ -156,7 +156,7 @@ class Multi {
     // Either undefined or an array. Fail hard if it's not an array
     if (args) {
       // Legacy support for passing in an array of arguments
-      for (let i = 0; i < args.length; i++) {
+      for (var i = 0; i < args.length; i++) {
         const command = args[i][0]
         const tmpArgs = args[i].slice(1)
         if (Array.isArray(command)) {
diff --git a/lib/utils.js b/lib/utils.js
index a422993fb5..90d43d6742 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -62,7 +62,7 @@ function clone (obj) {
   var copy
   if (Array.isArray(obj)) {
     copy = new Array(obj.length)
-    for (let i = 0; i < obj.length; i++) {
+    for (var i = 0; i < obj.length; i++) {
       copy[i] = clone(obj[i])
     }
     return copy
@@ -70,7 +70,7 @@ function clone (obj) {
   if (Object.prototype.toString.call(obj) === '[object Object]') {
     copy = {}
     const elements = Object.keys(obj)
-    for (let elem = elements.pop(); elem !== undefined; elem = elements.pop()) {
+    for (var elem = elements.pop(); elem !== undefined; elem = elements.pop()) {
       copy[elem] = clone(obj[elem])
     }
     return copy