diff --git a/ext/http/00_serve.js b/ext/http/00_serve.js
index a26c6604e0..422ce2fe31 100644
--- a/ext/http/00_serve.js
+++ b/ext/http/00_serve.js
@@ -682,8 +682,8 @@ function serveHttpOn(context, callback) {
 
   // Run the server
   const finished = (async () => {
+    const rid = context.serverRid;
     while (true) {
-      const rid = context.serverRid;
       let req;
       try {
         // Attempt to pull as many requests out of the queue as possible before awaiting. This API is
diff --git a/ext/webidl/00_webidl.js b/ext/webidl/00_webidl.js
index ca1c7c6064..9454dc3923 100644
--- a/ext/webidl/00_webidl.js
+++ b/ext/webidl/00_webidl.js
@@ -59,7 +59,6 @@ const {
   ReflectHas,
   ReflectOwnKeys,
   RegExpPrototypeTest,
-  RegExpPrototypeExec,
   SafeRegExp,
   SafeSet,
   SetPrototypeEntries,
@@ -403,11 +402,19 @@ converters.DOMString = function (V, prefix, context, opts = {}) {
   return String(V);
 };
 
-// deno-lint-ignore no-control-regex
-const IS_BYTE_STRING = new SafeRegExp(/^[\x00-\xFF]*$/);
+function isByteString(input) {
+  for (let i = 0; i < input.length; i++) {
+    if (StringPrototypeCharCodeAt(input, i) > 255) {
+      // If a character code is greater than 255, it means the string is not a byte string.
+      return false;
+    }
+  }
+  return true;
+}
+
 converters.ByteString = (V, prefix, context, opts) => {
   const x = converters.DOMString(V, prefix, context, opts);
-  if (RegExpPrototypeExec(IS_BYTE_STRING, x) === null) {
+  if (!isByteString(x)) {
     throw makeException(
       TypeError,
       "is not a valid ByteString",