diff --git a/.github/workflows/node.js.yml b/.github/workflows/node.js.yml
index bc95ab1..6b2f6da 100644
--- a/.github/workflows/node.js.yml
+++ b/.github/workflows/node.js.yml
@@ -16,7 +16,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [18.x]
+        node-version: [18.x, 20.x]
 
     steps:
     - uses: actions/checkout@v2
@@ -25,5 +25,4 @@ jobs:
       with:
         node-version: ${{ matrix.node-version }}
     - run: npm ci
-    - run: npm run build --if-present
     - run: npm test
diff --git a/package.json b/package.json
index 3d711c0..925cacc 100644
--- a/package.json
+++ b/package.json
@@ -27,7 +27,7 @@
     "prebuild": "npm run clean",
     "build": "tsc && tsc -p tsconfig.cjs.json && ts-node scripts/generate_cjs_pkgjson.ts",
     "prettier": "prettier --no-semi --tab-width 2 --write \"**/*.ts\"",
-    "test": "node --test --require ts-node/register \"test/index.ts\""
+    "test": "node --test --loader ts-node/esm \"test/index.ts\""
   },
   "repository": {
     "type": "git",
diff --git a/test/index.ts b/test/index.ts
index f873277..1f6a25c 100644
--- a/test/index.ts
+++ b/test/index.ts
@@ -1,6 +1,6 @@
 import test from "node:test"
 import { strict as assert } from "assert"
-import { ke2dairanization } from "../src"
+import { ke2dairanization } from "../src/index.ts"
 
 test("test words", async (t) => {
   await t.test("松平 健", async () => {
diff --git a/tsconfig.json b/tsconfig.json
index 9ac09a5..a642555 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -35,7 +35,7 @@
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
-    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution bundler' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
+    "allowImportingTsExtensions": true,                  /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution bundler' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolvePackageJsonExports": true,                /* Use the package.json 'exports' field when resolving package imports. */
     // "resolvePackageJsonImports": true,                /* Use the package.json 'imports' field when resolving imports. */
     // "customConditions": [],                           /* Conditions to set in addition to the resolver-specific defaults when resolving imports. */