diff --git a/lib/_http_client.js b/lib/_http_client.js
index 0eae2e7e58dd04..4aa6ee2fe342d1 100644
--- a/lib/_http_client.js
+++ b/lib/_http_client.js
@@ -110,7 +110,7 @@ function ClientRequest(input, options, cb) {
     options = Object.assign(input || {}, options);
   }
 
-  var agent = options.agent;
+  let agent = options.agent;
   const defaultAgent = options._defaultAgent || Agent.globalAgent;
   if (agent === false) {
     agent = new defaultAgent.constructor();
@@ -128,11 +128,11 @@ function ClientRequest(input, options, cb) {
   this.agent = agent;
 
   const protocol = options.protocol || defaultAgent.protocol;
-  var expectedProtocol = defaultAgent.protocol;
+  let expectedProtocol = defaultAgent.protocol;
   if (this.agent && this.agent.protocol)
     expectedProtocol = this.agent.protocol;
 
-  var path;
+  let path;
   if (options.path) {
     path = String(options.path);
     if (INVALID_PATH_REGEX.test(path))
@@ -157,7 +157,7 @@ function ClientRequest(input, options, cb) {
   if (options.timeout !== undefined)
     this.timeout = getTimerDuration(options.timeout, 'timeout');
 
-  var method = options.method;
+  let method = options.method;
   const methodIsString = (typeof method === 'string');
   if (method !== null && method !== undefined && !methodIsString) {
     throw new ERR_INVALID_ARG_TYPE('method', 'string', method);
@@ -196,7 +196,7 @@ function ClientRequest(input, options, cb) {
   this.parser = null;
   this.maxHeadersCount = null;
 
-  var called = false;
+  let called = false;
 
   if (this.agent) {
     // If there is an agent we should default to Connection:keep-alive,
@@ -215,20 +215,20 @@ function ClientRequest(input, options, cb) {
   const headersArray = Array.isArray(options.headers);
   if (!headersArray) {
     if (options.headers) {
-      var keys = Object.keys(options.headers);
-      for (var i = 0; i < keys.length; i++) {
-        var key = keys[i];
+      const keys = Object.keys(options.headers);
+      for (let i = 0; i < keys.length; i++) {
+        const key = keys[i];
         this.setHeader(key, options.headers[key]);
       }
     }
 
     if (host && !this.getHeader('host') && setHost) {
-      var hostHeader = host;
+      let hostHeader = host;
 
       // For the Host header, ensure that IPv6 addresses are enclosed
       // in square brackets, as defined by URI formatting
       // https://tools.ietf.org/html/rfc3986#section-3.2.2
-      var posColon = hostHeader.indexOf(':');
+      const posColon = hostHeader.indexOf(':');
       if (posColon !== -1 &&
           hostHeader.includes(':', posColon + 1) &&
           hostHeader.charCodeAt(0) !== 91/* '[' */) {
@@ -463,8 +463,8 @@ function socketOnData(d) {
     req.emit('error', ret);
   } else if (parser.incoming && parser.incoming.upgrade) {
     // Upgrade (if status code 101) or CONNECT
-    var bytesParsed = ret;
-    var res = parser.incoming;
+    const bytesParsed = ret;
+    const res = parser.incoming;
     req.res = res;
 
     socket.removeListener('data', socketOnData);
@@ -473,9 +473,9 @@ function socketOnData(d) {
     parser.finish();
     freeParser(parser, req, socket);
 
-    var bodyHead = d.slice(bytesParsed, d.length);
+    const bodyHead = d.slice(bytesParsed, d.length);
 
-    var eventName = req.method === 'CONNECT' ? 'connect' : 'upgrade';
+    const eventName = req.method === 'CONNECT' ? 'connect' : 'upgrade';
     if (req.listenerCount(eventName) > 0) {
       req.upgradeOrConnect = true;