diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b07e387..c6f9601 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -20,5 +20,6 @@ jobs:
           cache: "pnpm"
       - run: pnpm install
       - run: pnpm lint
+      - run: pnpm test:types
       - run: pnpm build
       - run: pnpm vitest run --coverage
diff --git a/package.json b/package.json
index 55d2341..d175da7 100644
--- a/package.json
+++ b/package.json
@@ -4,6 +4,7 @@
   "description": "A unified javascript build system",
   "repository": "unjs/unbuild",
   "license": "MIT",
+  "type": "module",
   "exports": {
     ".": {
       "import": "./dist/index.mjs"
@@ -24,7 +25,8 @@
     "prepack": "pnpm unbuild",
     "release": "pnpm test && changelogen --release --prerelease --publish && git push --follow-tags",
     "stub": "pnpm unbuild --stub",
-    "test": "pnpm lint && vitest run --coverage",
+    "test": "pnpm lint && pnpm test:types && vitest run --coverage",
+    "test:types": "tsc --noEmit",
     "unbuild": "jiti ./src/cli"
   },
   "dependencies": {
diff --git a/src/builders/mkdist/index.ts b/src/builders/mkdist/index.ts
index e306a47..73badb2 100644
--- a/src/builders/mkdist/index.ts
+++ b/src/builders/mkdist/index.ts
@@ -1,5 +1,5 @@
 import { relative } from "pathe";
-import { mkdist, MkdistOptions } from "mkdist";
+import { mkdist, type MkdistOptions } from "mkdist";
 import { symlink, rmdir } from "../../utils";
 import type { MkdistBuildEntry, BuildContext } from "../../types";
 import consola from "consola";
diff --git a/src/builders/rollup/plugins/esbuild.ts b/src/builders/rollup/plugins/esbuild.ts
index 459128f..226af34 100644
--- a/src/builders/rollup/plugins/esbuild.ts
+++ b/src/builders/rollup/plugins/esbuild.ts
@@ -1,10 +1,10 @@
 // Based on https://github.com/egoist/rollup-plugin-esbuild and nitropack fork (MIT)
-
-import { extname, relative } from "pathe";
 import type { Plugin, PluginContext } from "rollup";
-import { Loader, TransformResult, CommonOptions, transform } from "esbuild";
-import { createFilter } from "@rollup/pluginutils";
 import type { FilterPattern } from "@rollup/pluginutils";
+import type { Loader, TransformResult, CommonOptions } from "esbuild";
+import { transform } from "esbuild";
+import { extname, relative } from "pathe";
+import { createFilter } from "@rollup/pluginutils";
 
 const DefaultLoaders: { [ext: string]: Loader } = {
   ".js": "js",
diff --git a/src/builders/rollup/plugins/json.ts b/src/builders/rollup/plugins/json.ts
index e91c100..ed811c0 100644
--- a/src/builders/rollup/plugins/json.ts
+++ b/src/builders/rollup/plugins/json.ts
@@ -1,4 +1,4 @@
-import type { Plugin } from "rollup";
+import type { Plugin, TransformHook } from "rollup";
 import type { RollupJsonOptions } from "@rollup/plugin-json";
 import rollupJSONPlugin from "@rollup/plugin-json";
 
@@ -10,7 +10,7 @@ export function JSONPlugin(options: RollupJsonOptions): Plugin {
     ...plugin,
     name: "unbuild-json",
     transform(code, id) {
-      const res = plugin.transform!.call(this, code, id);
+      const res = (plugin.transform as TransformHook)!.call(this, code, id);
       if (
         res &&
         typeof res !== "string" &&
diff --git a/src/validate.ts b/src/validate.ts
index d7bf131..fa143cb 100644
--- a/src/validate.ts
+++ b/src/validate.ts
@@ -1,9 +1,9 @@
+import type { PackageJson } from "pkg-types";
+import type { BuildContext } from "./types";
 import { existsSync } from "node:fs";
 import chalk from "chalk";
 import { resolve } from "pathe";
-import { PackageJson } from "pkg-types";
 import { arrayIncludes, extractExportFilenames, getpkg, warn } from "./utils";
-import { BuildContext } from "./types";
 
 export function validateDependencies(ctx: BuildContext): void {
   const usedDependencies = new Set<string>();
diff --git a/test/auto.test.ts b/test/auto.test.ts
index b0f86e1..37ed996 100644
--- a/test/auto.test.ts
+++ b/test/auto.test.ts
@@ -132,6 +132,7 @@ describe("inferEntries", () => {
   it("handles types within exports`", () => {
     const result = inferEntries(
       {
+        // @ts-expect-error - fix pkg-types
         exports: {
           import: {
             types: "dist/test.d.mts",
@@ -166,6 +167,7 @@ describe("inferEntries", () => {
 
   it("ignores top-level exports", () => {
     expect(
+      // @ts-expect-error - fix pkg-types
       inferEntries({ exports: { "./*": "./*" } }, [
         "src/",
         "src/",
@@ -183,6 +185,7 @@ describe("inferEntries", () => {
     expect(
       inferEntries(
         {
+          // @ts-expect-error - fix pkg-types
           exports: {
             ".": "./dist/index.cjs",
             "first-test": "./dist/first-test.cjs",
@@ -219,6 +222,7 @@ describe("inferEntries", () => {
       warnings: [],
     });
     expect(
+      // @ts-expect-error - fix pkg-types
       inferEntries({ exports: { "./runtime/*": "./dist/runtime/*.mjs," } }, [
         "src/",
         "src/runtime/",
@@ -233,6 +237,7 @@ describe("inferEntries", () => {
     });
     expect(
       inferEntries(
+        // @ts-expect-error - fix pkg-types
         { exports: { "./runtime/*": { require: "./dist/runtime/*" } } },
         ["src/", "src/runtime/"],
       ),
diff --git a/test/fixture/build.config.ts b/test/fixture/build.config.ts
index d7064b5..985309b 100644
--- a/test/fixture/build.config.ts
+++ b/test/fixture/build.config.ts
@@ -25,6 +25,7 @@ export default defineBuildConfig([
       jiti: {
         transformOptions: {
           babel: {
+            // @ts-expect-error - type complexity
             plugins: [["@babel/plugin-transform-class-properties"]],
           },
         },
diff --git a/test/utils.test.ts b/test/utils.test.ts
index 59eee3e..76db030 100644
--- a/test/utils.test.ts
+++ b/test/utils.test.ts
@@ -27,11 +27,12 @@ describe("extractExportFilenames", () => {
     ]);
   });
   it("handles nested objects", () => {
+    // @ts-expect-error - fix pkg-types
     expect(extractExportFilenames({ require: "test" })).to.deep.equal([
       { file: "test", type: "cjs" },
     ]);
-    // @ts-ignore TODO: fix pkg-types
     expect(
+      // @ts-expect-error - fix pkg-types
       extractExportFilenames({
         require: { node: "test", other: { import: "this", require: "that" } },
       }),
diff --git a/test/validate.test.ts b/test/validate.test.ts
index 1fbcd0c..0842680 100644
--- a/test/validate.test.ts
+++ b/test/validate.test.ts
@@ -1,9 +1,9 @@
+import type { BuildEntry } from "../src/types.ts";
 import { fileURLToPath } from "node:url";
 import { consola } from "consola";
 import { join } from "pathe";
 import { describe, it, expect } from "vitest";
 import { validateDependencies, validatePackage } from "../src/validate";
-import { BuildEntry } from "../src/types";
 
 describe("validatePackage", () => {
   it("detects missing files", () => {
diff --git a/tsconfig.json b/tsconfig.json
index 3d4f70a..06c6a5e 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,16 +1,21 @@
 {
   "compilerOptions": {
     "target": "ESNext",
-    "module": "ESNext",
-    "moduleResolution": "Node",
+    "module": "Preserve",
+    "moduleResolution": "Bundler",
     "resolveJsonModule": true,
-    "esModuleInterop": true,
-    "outDir": "dist",
+    "esModuleInterop": false,
+    "allowSyntheticDefaultImports": true,
+    "skipLibCheck": true,
+    "allowJs": true,
+    "checkJs": true,
     "strict": true,
-    "declaration": true
+    "verbatimModuleSyntax": true,
+    "isolatedModules": true,
+    "forceConsistentCasingInFileNames": true,
+    "allowImportingTsExtensions": true,
+    "noImplicitOverride": true,
+    "noEmit": true
   },
-  "include": [
-    "src",
-    "test"
-  ]
+  "include": ["src", "test"]
 }