diff --git a/lib/web/websocket/constants.js b/lib/web/websocket/constants.js
index 76ed34a650e..45484042e61 100644
--- a/lib/web/websocket/constants.js
+++ b/lib/web/websocket/constants.js
@@ -21,8 +21,9 @@ const states = {
 }
 
 const sentCloseFrameState = {
-  SENT: 1,
-  RECEIVED: 2
+  NOT_SENT: 0,
+  SENT: 1 << 0,
+  RECEIVED: 1 << 1
 }
 
 const opcodes = {
diff --git a/lib/web/websocket/receiver.js b/lib/web/websocket/receiver.js
index 69cfa1b3da5..2e5abf37a8c 100644
--- a/lib/web/websocket/receiver.js
+++ b/lib/web/websocket/receiver.js
@@ -356,7 +356,7 @@ class ByteParser extends Writable {
 
       // Upon receiving such a frame, the other peer sends a
       // Close frame in response, if it hasn't already sent one.
-      if (!this.#handler.closeState.has(sentCloseFrameState.SENT)) {
+      if ((this.#handler.closeState & sentCloseFrameState.SENT) === 0) {
         // If an endpoint receives a Close frame and did not previously send a
         // Close frame, the endpoint MUST send a Close frame in response.  (When
         // sending a Close frame in response, the endpoint typically echos the
@@ -369,14 +369,14 @@ class ByteParser extends Writable {
         const closeFrame = new WebsocketFrameSend(body)
 
         this.#handler.socket.write(closeFrame.createFrame(opcodes.CLOSE))
-        this.#handler.closeState.add(sentCloseFrameState.SENT)
+        this.#handler.closeState |= sentCloseFrameState.SENT
       }
 
       // Upon either sending or receiving a Close control frame, it is said
       // that _The WebSocket Closing Handshake is Started_ and that the
       // WebSocket connection is in the CLOSING state.
       this.#handler.readyState = states.CLOSING
-      this.#handler.closeState.add(sentCloseFrameState.RECEIVED)
+      this.#handler.closeState |= sentCloseFrameState.RECEIVED
 
       return false
     } else if (opcode === opcodes.PING) {
@@ -385,7 +385,7 @@ class ByteParser extends Writable {
       // A Pong frame sent in response to a Ping frame must have identical
       // "Application data"
 
-      if (!this.#handler.closeState.has(sentCloseFrameState.RECEIVED)) {
+      if ((this.#handler.closeState & sentCloseFrameState.RECEIVED) === 0) {
         const frame = new WebsocketFrameSend(body)
 
         this.#handler.socket.write(frame.createFrame(opcodes.PONG))
diff --git a/lib/web/websocket/websocket.js b/lib/web/websocket/websocket.js
index 6d68bda43b3..c733989f521 100644
--- a/lib/web/websocket/websocket.js
+++ b/lib/web/websocket/websocket.js
@@ -39,7 +39,7 @@ const { channels } = require('../../core/diagnostics')
  *
  * @property {number} readyState
  * @property {import('stream').Duplex} socket
- * @property {Set<number>} closeState
+ * @property {number} closeState
  */
 
 // https://websockets.spec.whatwg.org/#interface-definition
@@ -84,7 +84,7 @@ class WebSocket extends EventTarget {
 
     readyState: states.CONNECTING,
     socket: null,
-    closeState: new Set()
+    closeState: sentCloseFrameState.NOT_SENT
   }
 
   #url
@@ -592,7 +592,7 @@ class WebSocket extends EventTarget {
       // to CLOSING (2).
       failWebsocketConnection(this.#handler, 1002, 'Connection was closed before it was established.')
       this.#handler.readyState = states.CLOSING
-    } else if (!this.#handler.closeState.has(sentCloseFrameState.SENT) && !this.#handler.closeState.has(sentCloseFrameState.RECEIVED)) {
+    } else if (this.#handler.closeState === sentCloseFrameState.NOT_SENT) {
       // Upon either sending or receiving a Close control frame, it is said
       // that _The WebSocket Closing Handshake is Started_ and that the
       // WebSocket connection is in the CLOSING state.
@@ -630,7 +630,7 @@ class WebSocket extends EventTarget {
 
       this.#handler.socket.write(frame.createFrame(opcodes.CLOSE))
 
-      this.#handler.closeState.add(sentCloseFrameState.SENT)
+      this.#handler.closeState |= sentCloseFrameState.SENT
 
       // Upon either sending or receiving a Close control frame, it is said
       // that _The WebSocket Closing Handshake is Started_ and that the
@@ -671,9 +671,7 @@ class WebSocket extends EventTarget {
     // If the TCP connection was closed after the
     // WebSocket closing handshake was completed, the WebSocket connection
     // is said to have been closed _cleanly_.
-    const wasClean =
-      this.#handler.closeState.has(sentCloseFrameState.SENT) &&
-      this.#handler.closeState.has(sentCloseFrameState.RECEIVED)
+    const wasClean = this.#handler.closeState === (sentCloseFrameState.SENT & sentCloseFrameState.RECEIVED)
 
     let code = 1005
     let reason = ''
@@ -683,7 +681,7 @@ class WebSocket extends EventTarget {
     if (result && !result.error) {
       code = result.code ?? 1005
       reason = result.reason
-    } else if (!this.#handler.closeState.has(sentCloseFrameState.RECEIVED)) {
+    } else if ((this.#handler.closeState & sentCloseFrameState.RECEIVED) === 0) {
       // If _The WebSocket
       // Connection is Closed_ and no Close control frame was received by the
       // endpoint (such as could occur if the underlying transport connection