diff --git a/index.d.ts b/index.d.ts
deleted file mode 100644
index 670a3ff..0000000
--- a/index.d.ts
+++ /dev/null
@@ -1,43 +0,0 @@
-import * as Http from 'http';
-import * as Https from 'https';
-import { Stream } from 'pump';
-import * as Undici from 'undici';
-
-interface QueryStringModule {
-  stringify(value: any): string;
-  parse(value: string): any;
-}
-
-interface Options {
-  base?: string;
-  http2?: boolean;
-  undici?: Undici.Pool.Options;
-  cacheURLs?: number;
-  requests?: {
-    http?: Http.Agent,
-    https?: Https.Agent
-  };
-  keepAliveMsecs?: number;
-  maxSockets?: number;
-  rejectUnauthorized?: boolean;
-  queryString?: QueryStringModule;
-}
-
-declare function fastProxy(options?: Options): {
-  proxy(
-    originReq: Http.IncomingMessage,
-    originRes: Http.ServerResponse,
-    source: string,
-    opts?: {
-      base?: string;
-      onResponse?(req: Http.IncomingMessage, res: Http.ServerResponse, stream: Stream): void;
-      rewriteRequestHeaders?(req: Http.IncomingMessage, headers: Http.IncomingHttpHeaders): Http.IncomingHttpHeaders;
-      rewriteHeaders?(headers: Http.OutgoingHttpHeaders): Http.OutgoingHttpHeaders;
-      request?: Http.RequestOptions;
-      queryString?: string;
-    }
-  ): void;
-  close(): void;
-}
-
-export default fastProxy
diff --git a/package.json b/package.json
index e201832..5ac5bce 100644
--- a/package.json
+++ b/package.json
@@ -3,10 +3,12 @@
   "version": "2.1.0",
   "description": "Forward your HTTP request to another server.",
   "main": "index.js",
-  "types": "index.d.ts",
+  "types": "types/index.d.ts",
   "scripts": {
-    "lint": "npx standard",
-    "test": "nyc mocha test/*.test.js",
+    "lint": "standard",
+    "test": "npm run test:unit && npm run test:typescript",
+    "test:unit": "nyc mocha test/*.test.js",
+    "test:typescript": "tsd",
     "bench": "( node benchmark/service.js & node benchmark/fast-proxy-0http-gateway.js & (sleep 5 && wrk -t8 -c8 -d30s http://127.0.0.1:8080/service/hi) )"
   },
   "repository": {
@@ -22,7 +24,7 @@
   "files": [
     "LICENSE",
     "README.md",
-    "index.d.ts",
+    "types/index.d.ts",
     "index.js",
     "lib/"
   ],
@@ -33,6 +35,7 @@
   },
   "homepage": "https://github.com/fastify/fast-proxy",
   "devDependencies": {
+    "@types/node": "^18.11.10",
     "0http": "^3.1.1",
     "body-parser": "^1.19.0",
     "chai": "^4.3.4",
@@ -45,7 +48,8 @@
     "restana": "^4.9.1",
     "self-cert": "^2.0.0",
     "standard": "^17.0.0",
-    "supertest": "^6.1.6"
+    "supertest": "^6.1.6",
+    "tsd": "^0.25.0"
   },
   "dependencies": {
     "end-of-stream": "^1.4.4",
diff --git a/types/index.d.ts b/types/index.d.ts
new file mode 100644
index 0000000..0d7f858
--- /dev/null
+++ b/types/index.d.ts
@@ -0,0 +1,50 @@
+import * as Http from 'http';
+import * as Https from 'https';
+import * as Undici from 'undici';
+
+type Stream = ReadableStream | WritableStream
+
+type FastProxy = (options?: fastProxy.FastProxyOptions) => {
+  proxy(
+    originReq: Http.IncomingMessage,
+    originRes: Http.ServerResponse,
+    source: string,
+    opts?: {
+      base?: string;
+      onResponse?(req: Http.IncomingMessage, res: Http.ServerResponse, stream: Stream): void;
+      rewriteRequestHeaders?(req: Http.IncomingMessage, headers: Http.IncomingHttpHeaders): Http.IncomingHttpHeaders;
+      rewriteHeaders?(headers: Http.OutgoingHttpHeaders): Http.OutgoingHttpHeaders;
+      request?: Http.RequestOptions;
+      queryString?: string;
+    }
+  ): void;
+  close(): void;
+}
+
+declare namespace fastProxy {
+  interface QueryStringModule {
+    stringify(value: any): string;
+    parse(value: string): any;
+  }
+
+  export interface FastProxyOptions {
+    base?: string;
+    http2?: boolean;
+    undici?: Undici.Pool.Options;
+    cacheURLs?: number;
+    requests?: {
+      http?: Http.Agent,
+      https?: Https.Agent
+    };
+    keepAliveMsecs?: number;
+    maxSockets?: number;
+    rejectUnauthorized?: boolean;
+    queryString?: QueryStringModule;
+  }
+
+  export const fastProxy: FastProxy
+  export { fastProxy as default }
+}
+
+declare function fastProxy(...params: Parameters<FastProxy>): ReturnType<FastProxy>
+export = fastProxy
diff --git a/types/index.test-d.ts b/types/index.test-d.ts
new file mode 100644
index 0000000..1c31fc7
--- /dev/null
+++ b/types/index.test-d.ts
@@ -0,0 +1,13 @@
+import fastProxy, { fastProxy as fastProxyNamed} from '..'
+import { expectAssignable, expectType } from 'tsd'
+
+const proxy = fastProxy({
+  base: 'http://127.0.0.1:3000'
+})
+fastProxyNamed({
+  base: 'http://127.0.0.1:3000'
+})
+
+expectType<typeof fastProxyNamed>(fastProxy)
+expectType<() => void>(proxy.close)
+expectAssignable<Function>(proxy.proxy)