diff --git a/benchmark/benchmark-from-msgpack-lite.ts b/benchmark/benchmark-from-msgpack-lite.ts
index c03cd0a..40ac6f9 100644
--- a/benchmark/benchmark-from-msgpack-lite.ts
+++ b/benchmark/benchmark-from-msgpack-lite.ts
@@ -1,7 +1,7 @@
 /* eslint-disable */
 // original: https://raw.githubusercontent.com/kawanet/msgpack-lite/master/lib/benchmark.js
 
-var msgpack_msgpack = require("../src");
+var msgpack_msgpack = require("../src/index.ts");
 
 var msgpack_node = try_require("msgpack");
 var msgpack_lite = try_require("msgpack-lite");
diff --git a/benchmark/decode-string.ts b/benchmark/decode-string.ts
index a6ea146..3e6bfbb 100644
--- a/benchmark/decode-string.ts
+++ b/benchmark/decode-string.ts
@@ -1,5 +1,5 @@
 /* eslint-disable no-console */
-import { utf8EncodeJs, utf8Count, utf8DecodeJs, utf8DecodeTD } from "../src/utils/utf8";
+import { utf8EncodeJs, utf8Count, utf8DecodeJs, utf8DecodeTD } from "../src/utils/utf8.ts";
 
 // @ts-ignore
 import Benchmark from "benchmark";
diff --git a/benchmark/encode-string.ts b/benchmark/encode-string.ts
index 3f6aac6..df1b283 100644
--- a/benchmark/encode-string.ts
+++ b/benchmark/encode-string.ts
@@ -1,5 +1,5 @@
 /* eslint-disable no-console */
-import { utf8EncodeJs, utf8Count, utf8EncodeTE } from "../src/utils/utf8";
+import { utf8EncodeJs, utf8Count, utf8EncodeTE } from "../src/utils/utf8.ts";
 
 // @ts-ignore
 import Benchmark from "benchmark";
diff --git a/benchmark/key-decoder.ts b/benchmark/key-decoder.ts
index 594bbab..dec38f3 100644
--- a/benchmark/key-decoder.ts
+++ b/benchmark/key-decoder.ts
@@ -1,9 +1,11 @@
 /* eslint-disable no-console */
-import { utf8EncodeJs, utf8Count, utf8DecodeJs } from "../src/utils/utf8";
+import { utf8EncodeJs, utf8Count, utf8DecodeJs } from "../src/utils/utf8.ts";
+import { CachedKeyDecoder } from "../src/CachedKeyDecoder.ts";
+
+import data from "./benchmark-from-msgpack-lite-data.json" with { type: "json" };
 
 // @ts-ignore
 import Benchmark from "benchmark";
-import { CachedKeyDecoder } from "../src/CachedKeyDecoder";
 
 type InputType = {
   bytes: Uint8Array;
@@ -11,7 +13,7 @@ type InputType = {
   str: string;
 };
 
-const keys: Array<InputType> = Object.keys(require("./benchmark-from-msgpack-lite-data.json")).map((str) => {
+const keys: Array<InputType> = Object.keys(data).map((str) => {
   const byteLength = utf8Count(str);
   const bytes = new Uint8Array(new ArrayBuffer(byteLength));
   utf8EncodeJs(str, bytes, 0);
diff --git a/benchmark/package.json b/benchmark/package.json
index 161581b..ddc30b8 100644
--- a/benchmark/package.json
+++ b/benchmark/package.json
@@ -2,6 +2,7 @@
   "name": "@msgpack/msgpack-benchmark",
   "private": true,
   "version": "0.0.0",
+  "type": "module",
   "scripts": {
     "update-dependencies": "npx rimraf node_modules/ package-lock.json ; npm install ; npm audit fix --force ; git restore package.json ; npm install"
   },
diff --git a/benchmark/profile-decode.ts b/benchmark/profile-decode.ts
index 081ddab..512d87e 100644
--- a/benchmark/profile-decode.ts
+++ b/benchmark/profile-decode.ts
@@ -1,4 +1,4 @@
-import { encode, decode, decodeAsync } from "../src";
+import { encode, decode, decodeAsync } from "../src/index.ts";
 // @ts-ignore
 import _ from "lodash";
 const data = require("./benchmark-from-msgpack-lite-data.json");
diff --git a/benchmark/profile-encode.ts b/benchmark/profile-encode.ts
index 6efcf01..245e71b 100644
--- a/benchmark/profile-encode.ts
+++ b/benchmark/profile-encode.ts
@@ -1,4 +1,4 @@
-import { encode } from "../src";
+import { encode } from "../src/index.ts";
 // @ts-ignore
 import _ from "lodash";
 
diff --git a/benchmark/string.ts b/benchmark/string.ts
index b801394..4f11f30 100644
--- a/benchmark/string.ts
+++ b/benchmark/string.ts
@@ -1,5 +1,5 @@
 /* eslint-disable no-console */
-import { encode, decode } from "../src";
+import { encode, decode } from "../src/index.ts";
 
 const ascii = "A".repeat(40000);
 const emoji = "🌏".repeat(20000);
diff --git a/benchmark/sync-vs-async.ts b/benchmark/sync-vs-async.ts
index 6981932..620438e 100644
--- a/benchmark/sync-vs-async.ts
+++ b/benchmark/sync-vs-async.ts
@@ -1,12 +1,14 @@
-#!ts-node
+#!/usr/bin/env node
 /* eslint-disable no-console */
 
-import { encode, decode, decodeAsync, decodeArrayStream } from "../src";
-import { writeFileSync, unlinkSync, readFileSync, createReadStream } from "fs";
-import { deepStrictEqual } from "assert";
+import { encode, decode, decodeAsync, decodeArrayStream } from "../src/index.ts";
+import { writeFileSync, unlinkSync, readFileSync, createReadStream } from "node:fs";
+import { deepStrictEqual } from "node:assert";
+
+type Data = { id: number; score: number; title: string; content: string; createdAt: Date };
 
 (async () => {
-  const data = [];
+  const data: Data[] = [];
   for (let i = 0; i < 1000; i++) {
     const id = i + 1;
     data.push({
diff --git a/benchmark/timestamp-ext.ts b/benchmark/timestamp-ext.ts
index ba96a22..318b445 100644
--- a/benchmark/timestamp-ext.ts
+++ b/benchmark/timestamp-ext.ts
@@ -1,4 +1,4 @@
-import { encode, decode } from "../src";
+import { encode, decode } from "../src/index.ts";
 
 const data = new Array(100).fill(new Date());