diff --git a/lib/reply.js b/lib/reply.js
index c3c3bfc7bf..45db78b96e 100644
--- a/lib/reply.js
+++ b/lib/reply.js
@@ -203,10 +203,8 @@ Reply.prototype.getHeaders = function () {
 
 Reply.prototype.hasHeader = function (key) {
   key = key.toLowerCase()
-  if (this[kReplyHeaders][key] !== undefined) {
-    return true
-  }
-  return this.raw.hasHeader(key)
+
+  return this[kReplyHeaders][key] !== undefined || this.raw.hasHeader(key)
 }
 
 Reply.prototype.removeHeader = function (key) {
@@ -216,25 +214,24 @@ Reply.prototype.removeHeader = function (key) {
   return this
 }
 
-Reply.prototype.header = function (key, value) {
-  const _key = key.toLowerCase()
-
-  // default the value to ''
-  value = value === undefined ? '' : value
+Reply.prototype.header = function (key, value = '') {
+  key = key.toLowerCase()
 
-  if (this[kReplyHeaders][_key] && _key === 'set-cookie') {
+  if (this[kReplyHeaders][key] && key === 'set-cookie') {
     // https://tools.ietf.org/html/rfc7230#section-3.2.2
-    if (typeof this[kReplyHeaders][_key] === 'string') {
-      this[kReplyHeaders][_key] = [this[kReplyHeaders][_key]]
+    if (typeof this[kReplyHeaders][key] === 'string') {
+      this[kReplyHeaders][key] = [this[kReplyHeaders][key]]
     }
+
     if (Array.isArray(value)) {
-      Array.prototype.push.apply(this[kReplyHeaders][_key], value)
+      this[kReplyHeaders][key].push(...value)
     } else {
-      this[kReplyHeaders][_key].push(value)
+      this[kReplyHeaders][key].push(value)
     }
   } else {
-    this[kReplyHeaders][_key] = value
+    this[kReplyHeaders][key] = value
   }
+
   return this
 }
 
@@ -245,6 +242,7 @@ Reply.prototype.headers = function (headers) {
     const key = keys[i]
     this.header(key, headers[key])
   }
+
   return this
 }
 
@@ -279,8 +277,7 @@ Reply.prototype.trailer = function (key, fn) {
 }
 
 Reply.prototype.hasTrailer = function (key) {
-  if (this[kReplyTrailers] === null) return false
-  return this[kReplyTrailers][key.toLowerCase()] !== undefined
+  return this[kReplyTrailers]?.[key.toLowerCase()] !== undefined
 }
 
 Reply.prototype.removeTrailer = function (key) {
@@ -330,8 +327,7 @@ Reply.prototype.redirect = function (code, url) {
     code = this[kReplyHasStatusCode] ? this.raw.statusCode : 302
   }
 
-  this.header('location', url).code(code).send()
-  return this
+  return this.header('location', url).code(code).send()
 }
 
 Reply.prototype.callNotFound = function () {
@@ -485,9 +481,12 @@ function onSendEnd (reply, payload) {
   }
 
   if (reply[kReplyTrailers] === null) {
-    if (!reply[kReplyHeaders]['content-length']) {
-      reply[kReplyHeaders]['content-length'] = '' + Buffer.byteLength(payload)
-    } else if (req.raw.method !== 'HEAD' && reply[kReplyHeaders]['content-length'] !== Buffer.byteLength(payload)) {
+    const contentLength = reply[kReplyHeaders]['content-length']
+    if (!contentLength ||
+        (req.raw.method !== 'HEAD' &&
+         parseInt(contentLength, 10) !== Buffer.byteLength(payload)
+        )
+    ) {
       reply[kReplyHeaders]['content-length'] = '' + Buffer.byteLength(payload)
     }
   }