diff --git a/lib/core/util.js b/lib/core/util.js
index 6c2e1e55d21..ce95064e89a 100644
--- a/lib/core/util.js
+++ b/lib/core/util.js
@@ -280,13 +280,13 @@ function parseRawHeaders (headers) {
   let contentDispositionIdx = -1
 
   for (let n = 0; n < headers.length; n += 2) {
-    const key = headers[n + 0].toString()
+    const key = headerNameToString(headers[n])
     const val = headers[n + 1].toString('utf8')
 
-    if (key.length === 14 && (key === 'content-length' || key.toLowerCase() === 'content-length')) {
+    if (key === 'content-length') {
       ret.push(key, val)
       hasContentLength = true
-    } else if (key.length === 19 && (key === 'content-disposition' || key.toLowerCase() === 'content-disposition')) {
+    } else if (key === 'content-disposition') {
       contentDispositionIdx = ret.push(key, val) - 1
     } else {
       ret.push(key, val)
diff --git a/lib/handler/RedirectHandler.js b/lib/handler/RedirectHandler.js
index 34bba185d96..d8e96ddd844 100644
--- a/lib/handler/RedirectHandler.js
+++ b/lib/handler/RedirectHandler.js
@@ -176,7 +176,7 @@ function parseLocation (statusCode, headers) {
   }
 
   for (let i = 0; i < headers.length; i += 2) {
-    if (headers[i].toString().toLowerCase() === 'location') {
+    if (headers[i].length === 8 && util.headerNameToString(headers[i]) === 'location') {
       return headers[i + 1]
     }
   }
@@ -184,12 +184,17 @@ function parseLocation (statusCode, headers) {
 
 // https://tools.ietf.org/html/rfc7231#section-6.4.4
 function shouldRemoveHeader (header, removeContent, unknownOrigin) {
-  return (
-    (header.length === 4 && header.toString().toLowerCase() === 'host') ||
-    (removeContent && header.toString().toLowerCase().indexOf('content-') === 0) ||
-    (unknownOrigin && header.length === 13 && header.toString().toLowerCase() === 'authorization') ||
-    (unknownOrigin && header.length === 6 && header.toString().toLowerCase() === 'cookie')
-  )
+  if (header.length === 4) {
+    return util.headerNameToString(header) === 'host'
+  }
+  if (removeContent && util.headerNameToString(header).startsWith('content-')) {
+    return true
+  }
+  if (unknownOrigin && (header.length === 13 || header.length === 6)) {
+    const name = util.headerNameToString(header)
+    return name === 'authorization' || name === 'cookie'
+  }
+  return false
 }
 
 // https://tools.ietf.org/html/rfc7231#section-6.4