diff --git a/lib/fetch/index.js b/lib/fetch/index.js
index b45ed74cf02..f0f67b475a3 100644
--- a/lib/fetch/index.js
+++ b/lib/fetch/index.js
@@ -37,7 +37,10 @@ const {
   isErrorLike,
   fullyReadBody,
   readableStreamClose,
-  isomorphicEncode
+  isomorphicEncode,
+  urlIsLocal,
+  urlIsHttpHttpsScheme,
+  urlHasHttpsScheme
 } = require('./util')
 const { kState, kHeaders, kGuard, kRealm, kHeadersCaseInsensitive } = require('./symbols')
 const assert = require('assert')
@@ -272,7 +275,7 @@ function finalizeAndReportTiming (response, initiatorType = 'other') {
   let cacheState = response.cacheState
 
   // 6. If originalURL’s scheme is not an HTTP(S) scheme, then return.
-  if (!/^https?:/.test(originalURL.protocol)) {
+  if (!urlIsHttpHttpsScheme(originalURL)) {
     return
   }
 
@@ -530,10 +533,7 @@ async function mainFetch (fetchParams, recursive = false) {
 
   // 3. If request’s local-URLs-only flag is set and request’s current URL is
   // not local, then set response to a network error.
-  if (
-    request.localURLsOnly &&
-    !/^(about|blob|data):/.test(requestCurrentURL(request).protocol)
-  ) {
+  if (request.localURLsOnly && !urlIsLocal(requestCurrentURL(request))) {
     response = makeNetworkError('local URLs only')
   }
 
@@ -623,7 +623,7 @@ async function mainFetch (fetchParams, recursive = false) {
       }
 
       // request’s current URL’s scheme is not an HTTP(S) scheme
-      if (!/^https?:/.test(requestCurrentURL(request).protocol)) {
+      if (!urlIsHttpHttpsScheme(requestCurrentURL(request))) {
         // Return a network error.
         return makeNetworkError('URL scheme must be a HTTP(S) scheme')
       }
@@ -1130,7 +1130,7 @@ async function httpRedirectFetch (fetchParams, response) {
 
   // 6. If locationURL’s scheme is not an HTTP(S) scheme, then return a network
   // error.
-  if (!/^https?:/.test(locationURL.protocol)) {
+  if (!urlIsHttpHttpsScheme(locationURL)) {
     return makeNetworkError('URL scheme must be a HTTP(S) scheme')
   }
 
@@ -1399,7 +1399,7 @@ async function httpNetworkOrCacheFetch (
   //    header if httpRequest’s header list contains that header’s name.
   //    TODO: https://github.com/whatwg/fetch/issues/1285#issuecomment-896560129
   if (!httpRequest.headersList.contains('accept-encoding')) {
-    if (/^https:/.test(requestCurrentURL(httpRequest).protocol)) {
+    if (urlHasHttpsScheme(requestCurrentURL(httpRequest))) {
       httpRequest.headersList.append('accept-encoding', 'br, gzip, deflate')
     } else {
       httpRequest.headersList.append('accept-encoding', 'gzip, deflate')
diff --git a/lib/fetch/util.js b/lib/fetch/util.js
index 2d8977f17ba..4e44d9012af 100644
--- a/lib/fetch/util.js
+++ b/lib/fetch/util.js
@@ -64,7 +64,7 @@ function requestBadPort (request) {
 
   // 2. If url’s scheme is an HTTP(S) scheme and url’s port is a bad port,
   // then return blocked.
-  if (/^https?:/.test(url.protocol) && badPorts.includes(url.port)) {
+  if (urlIsHttpHttpsScheme(url) && badPorts.includes(url.port)) {
     return 'blocked'
   }
 
@@ -285,7 +285,7 @@ function appendRequestOriginHeader (request) {
       case 'strict-origin':
       case 'strict-origin-when-cross-origin':
         // If request’s origin is a tuple origin, its scheme is "https", and request’s current URL’s scheme is not "https", then set serializedOrigin to `null`.
-        if (/^https:/.test(request.origin) && !/^https:/.test(requestCurrentURL(request))) {
+        if (request.origin && urlHasHttpsScheme(request.origin) && !urlHasHttpsScheme(requestCurrentURL(request))) {
           serializedOrigin = null
         }
         break
@@ -944,6 +944,41 @@ async function readAllBytes (reader, successSteps, failureSteps) {
   }
 }
 
+/**
+ * @see https://fetch.spec.whatwg.org/#is-local
+ * @param {URL} url
+ */
+function urlIsLocal (url) {
+  assert('protocol' in url) // ensure it's a url object
+
+  const protocol = url.protocol
+
+  return protocol === 'about:' || protocol === 'blob:' || protocol === 'data:'
+}
+
+/**
+ * @param {string|URL} url
+ */
+function urlHasHttpsScheme (url) {
+  if (typeof url === 'string') {
+    return url.startsWith('https:')
+  }
+
+  return url.protocol === 'https:'
+}
+
+/**
+ * @see https://fetch.spec.whatwg.org/#http-scheme
+ * @param {URL} url
+ */
+function urlIsHttpHttpsScheme (url) {
+  assert('protocol' in url) // ensure it's a url object
+
+  const protocol = url.protocol
+
+  return protocol === 'http:' || protocol === 'https:'
+}
+
 /**
  * Fetch supports node >= 16.8.0, but Object.hasOwn was added in v16.9.0.
  */
@@ -988,5 +1023,8 @@ module.exports = {
   isReadableStreamLike,
   readableStreamClose,
   isomorphicEncode,
-  isomorphicDecode
+  isomorphicDecode,
+  urlIsLocal,
+  urlHasHttpsScheme,
+  urlIsHttpHttpsScheme
 }