diff --git a/package-lock.json b/package-lock.json
index 3125c1d..52ca72a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -15,6 +15,7 @@
         "@commitlint/cli": "^20.5.0",
         "@commitlint/config-conventional": "^20.5.0",
         "@eslint/js": "^10.0.1",
+        "@types/node": "^24.0.0",
         "@vitest/coverage-istanbul": "^4.1.2",
         "eslint": "^10.1.0",
         "eslint-config-prettier": "^10.1.8",
@@ -2488,14 +2489,13 @@
       "license": "MIT"
     },
     "node_modules/@types/node": {
-      "version": "25.3.5",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-25.3.5.tgz",
-      "integrity": "sha512-oX8xrhvpiyRCQkG1MFchB09f+cXftgIXb3a7UUa4Y3wpmZPw5tyZGTLWhlESOLq1Rq6oDlc8npVU2/9xiCuXMA==",
+      "version": "24.12.0",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-24.12.0.tgz",
+      "integrity": "sha512-GYDxsZi3ChgmckRT9HPU0WEhKLP08ev/Yfcq2AstjrDASOYCSXeyjDsHg4v5t4jOj7cyDX3vmprafKlWIG9MXQ==",
       "dev": true,
       "license": "MIT",
-      "peer": true,
       "dependencies": {
-        "undici-types": "~7.18.0"
+        "undici-types": "~7.16.0"
       }
     },
     "node_modules/@typescript-eslint/types": {
@@ -5783,12 +5783,11 @@
       }
     },
     "node_modules/undici-types": {
-      "version": "7.18.2",
-      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-7.18.2.tgz",
-      "integrity": "sha512-AsuCzffGHJybSaRrmr5eHr81mwJU3kjw6M+uprWvCXiNeN9SOGwQ3Jn8jb8m3Z6izVgknn1R0FTCEAP2QrLY/w==",
+      "version": "7.16.0",
+      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-7.16.0.tgz",
+      "integrity": "sha512-Zz+aZWSj8LE6zoxD+xrjh4VfkIG8Ya6LvYkZqtUQGJPZjYl53ypCaUwWqo7eI0x66KBGeRo+mlBEkMSeSZ38Nw==",
       "dev": true,
-      "license": "MIT",
-      "peer": true
+      "license": "MIT"
     },
     "node_modules/unenv": {
       "version": "2.0.0-rc.24",
diff --git a/package.json b/package.json
index 88a5f83..be91b30 100644
--- a/package.json
+++ b/package.json
@@ -8,6 +8,7 @@
     "@commitlint/cli": "^20.5.0",
     "@commitlint/config-conventional": "^20.5.0",
     "@eslint/js": "^10.0.1",
+    "@types/node": "^24.0.0",
     "@vitest/coverage-istanbul": "^4.1.2",
     "eslint": "^10.1.0",
     "eslint-config-prettier": "^10.1.8",
diff --git a/test/unit/typescript-config.test.js b/test/unit/typescript-config.test.js
new file mode 100644
index 0000000..e69ffaa
--- /dev/null
+++ b/test/unit/typescript-config.test.js
@@ -0,0 +1,19 @@
+// @vitest-environment node
+
+import { createRequire } from 'node:module';
+
+import { describe, expect, it } from 'vitest';
+
+const require = createRequire(import.meta.url);
+const tsconfig = require('../../tsconfig.json');
+const packageJson = require('../../package.json');
+
+describe('TypeScript config', () => {
+  it('explicitly includes Node.js types for mixed runtime files', () => {
+    expect(tsconfig.compilerOptions.types).toContain('node');
+  });
+
+  it('declares Node.js typings as a dev dependency', () => {
+    expect(packageJson.devDependencies['@types/node']).toBeTruthy();
+  });
+});
diff --git a/tsconfig.json b/tsconfig.json
index 93f2536..d4a01f7 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -9,7 +9,8 @@
     "noEmit": true,
     "skipLibCheck": true,
     "strict": true,
-    "target": "ES2022"
+    "target": "ES2022",
+    "types": ["node"]
   },
   "exclude": ["node_modules", "dist", "coverage"],
   "include": ["src/**/*", "test/**/*", "node_modules/@cloudflare/vitest-pool-workers/types/**/*"]