diff --git a/.changeset/chat-message-edit-timestamp.md b/.changeset/chat-message-edit-timestamp.md
new file mode 100644
index 00000000..09e58511
--- /dev/null
+++ b/.changeset/chat-message-edit-timestamp.md
@@ -0,0 +1,5 @@
+---
+'@livekit/rtc-node': patch
+---
+
+Fix `ChatMessage.editTimestamp` being `NaN` instead of `undefined` for a message that was never edited.
diff --git a/packages/livekit-rtc/src/participant.ts b/packages/livekit-rtc/src/participant.ts
index 07ed90a4..a7d7bbc6 100644
--- a/packages/livekit-rtc/src/participant.ts
+++ b/packages/livekit-rtc/src/participant.ts
@@ -104,7 +104,7 @@ import type { RemoteTrackPublication, TrackPublication } from './track_publicati
 import { LocalTrackPublication } from './track_publication.js';
 import type { Transcription } from './transcription.js';
 import type { ChatMessage } from './types.js';
-import { byteStreamInfoFromProto, textStreamInfoFromProto } from './utils.js';
+import { byteStreamInfoFromProto, chatMessageFromProto, textStreamInfoFromProto } from './utils.js';
 import { numberToBigInt } from './utils.js';
 
 export abstract class Participant {
@@ -651,13 +651,7 @@ export class LocalParticipant extends Participant {
 
     switch (cb.message.case) {
       case 'chatMessage':
-        const { id, timestamp, editTimestamp, message } = cb.message.value!;
-        return {
-          id: id!,
-          timestamp: Number(timestamp),
-          editTimestamp: Number(editTimestamp),
-          message: message!,
-        };
+        return chatMessageFromProto(cb.message.value!);
       case 'error':
       default:
         throw new Error(cb.message.value);
@@ -698,13 +692,7 @@ export class LocalParticipant extends Participant {
 
     switch (cb.message.case) {
       case 'chatMessage':
-        const { id, timestamp, editTimestamp, message } = cb.message.value!;
-        return {
-          id: id!,
-          timestamp: Number(timestamp),
-          editTimestamp: Number(editTimestamp),
-          message: message!,
-        };
+        return chatMessageFromProto(cb.message.value!);
       case 'error':
       default:
         throw new Error(cb.message.value);
diff --git a/packages/livekit-rtc/src/room.ts b/packages/livekit-rtc/src/room.ts
index 4ed47938..173dcdc4 100644
--- a/packages/livekit-rtc/src/room.ts
+++ b/packages/livekit-rtc/src/room.ts
@@ -55,6 +55,7 @@ import type { ChatMessage } from './types.js';
 import {
   bigIntToNumber,
   byteStreamInfoFromProto,
+  chatMessageFromProto,
   numberToBigInt,
   textStreamInfoFromProto,
 } from './utils.js';
@@ -825,14 +826,7 @@ export class Room extends (EventEmitter as new () => TypedEmitter<RoomCallbacks>
       }
     } else if (ev.case == 'chatMessage') {
       const participant = this.retrieveParticipantByIdentity(ev.value.participantIdentity!);
-      const { id, message: messageText, timestamp, editTimestamp, generated } = ev.value.message!;
-      const message: ChatMessage = {
-        id: id!,
-        message: messageText!,
-        timestamp: Number(timestamp),
-        editTimestamp: Number(editTimestamp),
-        generated,
-      };
+      const message: ChatMessage = chatMessageFromProto(ev.value.message!);
       this.emit(RoomEvent.ChatMessage, message, participant);
     } else if (ev.case == 'dataPacketReceived') {
       // Can be undefined if the data is sent from a Server SDK
diff --git a/packages/livekit-rtc/src/utils.test.ts b/packages/livekit-rtc/src/utils.test.ts
index 35ac904b..deb7f3ca 100644
--- a/packages/livekit-rtc/src/utils.test.ts
+++ b/packages/livekit-rtc/src/utils.test.ts
@@ -1,8 +1,9 @@
 // SPDX-FileCopyrightText: 2024 LiveKit, Inc.
 //
 // SPDX-License-Identifier: Apache-2.0
+import { ChatMessage as ProtoChatMessage } from '@livekit/rtc-ffi-bindings';
 import { describe, expect, it } from 'vitest';
-import { splitUtf8 } from './utils.js';
+import { chatMessageFromProto, splitUtf8 } from './utils.js';
 
 describe('splitUtf8', () => {
   it('splits a string into chunks of the given size', () => {
@@ -49,3 +50,34 @@ describe('splitUtf8', () => {
     expect(splitUtf8('', 5)).toEqual([]);
   });
 });
+
+describe('chatMessageFromProto', () => {
+  it('leaves editTimestamp undefined for a message that was never edited', () => {
+    const message = chatMessageFromProto(
+      new ProtoChatMessage({ id: 'msg-1', message: 'hello', timestamp: 1700000000000n }),
+    );
+
+    expect(message).toEqual({
+      id: 'msg-1',
+      message: 'hello',
+      timestamp: 1700000000000,
+      editTimestamp: undefined,
+      generated: undefined,
+    });
+  });
+
+  it('converts editTimestamp and generated for an edited message', () => {
+    const message = chatMessageFromProto(
+      new ProtoChatMessage({
+        id: 'msg-2',
+        message: 'hello again',
+        timestamp: 1700000000000n,
+        editTimestamp: 1700000005000n,
+        generated: true,
+      }),
+    );
+
+    expect(message.editTimestamp).toBe(1700000005000);
+    expect(message.generated).toBe(true);
+  });
+});
diff --git a/packages/livekit-rtc/src/utils.ts b/packages/livekit-rtc/src/utils.ts
index 1c274d59..1babb4ba 100644
--- a/packages/livekit-rtc/src/utils.ts
+++ b/packages/livekit-rtc/src/utils.ts
@@ -3,9 +3,11 @@
 // SPDX-License-Identifier: Apache-2.0
 import type {
   ByteStreamInfo as ProtoByteStreamInfo,
+  ChatMessage as ProtoChatMessage,
   TextStreamInfo as ProtoTextStreamInfo,
 } from '@livekit/rtc-ffi-bindings';
 import type { ByteStreamInfo, TextStreamInfo } from './data_streams/types.js';
+import type { ChatMessage } from './types.js';
 
 /** convert bigints to numbers preserving undefined values */
 export function bigIntToNumber<T extends bigint | undefined>(
@@ -70,3 +72,14 @@ export function byteStreamInfoFromProto(info: ProtoByteStreamInfo): ByteStreamIn
     attributes: info.attributes,
   };
 }
+
+/** @internal */
+export function chatMessageFromProto(info: ProtoChatMessage): ChatMessage {
+  return {
+    id: info.id!,
+    message: info.message!,
+    timestamp: bigIntToNumber(info.timestamp!),
+    editTimestamp: bigIntToNumber(info.editTimestamp),
+    generated: info.generated,
+  };
+}