diff --git a/types/got/got-tests.ts b/types/got/got-tests.ts
index 467211a87d..8aae7f300d 100644
--- a/types/got/got-tests.ts
+++ b/types/got/got-tests.ts
@@ -21,35 +21,35 @@ got('todomvc.com')
 
 got('todomvc.com').cancel();
 
-got('todomvc.com', {json: true}).then((response) => {
+got('todomvc.com', { json: true }).then((response) => {
     response.body; // $ExpectType any
 });
 
-got('todomvc.com', {json: true, body: {}}).then((response) => {
+got('todomvc.com', { json: true, body: {} }).then((response) => {
     response.body; // $ExpectType any
 });
 
-got('todomvc.com', {json: true, body: [{}]}).then((response) => {
+got('todomvc.com', { json: true, body: [{}] }).then((response) => {
     response.body; // $ExpectType any
 });
 
-got('todomvc.com', {json: true, form: true}).then((response) => {
+got('todomvc.com', { json: true, form: true }).then((response) => {
     response.body; // $ExpectType any
 });
 
-got('todomvc.com', {json: true, form: true, encoding: null}).then((response) => {
+got('todomvc.com', { json: true, form: true, encoding: null }).then((response) => {
     response.body; // $ExpectType any
 });
 
-got('todomvc.com', {json: true, form: true, encoding: null, hostname: 'todomvc'}).then((response) => {
+got('todomvc.com', { json: true, form: true, encoding: null, hostname: 'todomvc' }).then((response) => {
     response.body; // $ExpectType any
 });
 
-got('todomvc.com', {form: true}).then(response => str = response.body);
-got('todomvc.com', {form: true, body: {}}).then(response => str = response.body);
-got('todomvc.com', {form: true, body: [{}]}).then(response => str = response.body);
-got('todomvc.com', {form: true, body: [{}], encoding: null}).then(response => buf = response.body);
-got('todomvc.com', {form: true, body: [{}], encoding: 'utf8'}).then(response => str = response.body);
+got('todomvc.com', { form: true }).then(response => str = response.body);
+got('todomvc.com', { form: true, body: {} }).then(response => str = response.body);
+got('todomvc.com', { form: true, body: [{}] }).then(response => str = response.body);
+got('todomvc.com', { form: true, body: [{}], encoding: null }).then(response => buf = response.body);
+got('todomvc.com', { form: true, body: [{}], encoding: 'utf8' }).then(response => str = response.body);
 got('todomvc.com', {
     form: true,
     body: [{}],
@@ -68,21 +68,21 @@ got('todomvc.com', {
     body: [{}],
     encoding: 'utf8',
     hostname: 'todomvc',
-    timeout: {connect: 20, request: 20, socket: 20}
+    timeout: { connect: 20, request: 20, socket: 20 }
 }).then(response => str = response.body);
 // following must lead to type checking error: got('todomvc.com', {form: true, body: ''}).then(response => str = response.body);
 
-got('todomvc.com', {encoding: null, hostname: 'todomvc'}).then(response => buf = response.body);
-got('todomvc.com', {encoding: 'utf8', hostname: 'todomvc'}).then(response => str = response.body);
+got('todomvc.com', { encoding: null, hostname: 'todomvc' }).then(response => buf = response.body);
+got('todomvc.com', { encoding: 'utf8', hostname: 'todomvc' }).then(response => str = response.body);
 
-got('todomvc.com', {hostname: 'todomvc'}).then(response => str = response.body);
+got('todomvc.com', { hostname: 'todomvc' }).then(response => str = response.body);
 
-got.get('todomvc.com', {hostname: 'todomvc'}).then(response => str = response.body);
-got.post('todomvc.com', {hostname: 'todomvc'}).then(response => str = response.body);
-got.put('todomvc.com', {hostname: 'todomvc'}).then(response => str = response.body);
-got.patch('todomvc.com', {hostname: 'todomvc'}).then(response => str = response.body);
-got.head('todomvc.com', {hostname: 'todomvc'}).then(response => str = response.body);
-got.delete('todomvc.com', {hostname: 'todomvc'}).then(response => str = response.body);
+got.get('todomvc.com', { hostname: 'todomvc' }).then(response => str = response.body);
+got.post('todomvc.com', { hostname: 'todomvc' }).then(response => str = response.body);
+got.put('todomvc.com', { hostname: 'todomvc' }).then(response => str = response.body);
+got.patch('todomvc.com', { hostname: 'todomvc' }).then(response => str = response.body);
+got.head('todomvc.com', { hostname: 'todomvc' }).then(response => str = response.body);
+got.delete('todomvc.com', { hostname: 'todomvc' }).then(response => str = response.body);
 
 got.stream('todomvc.com').pipe(fs.createWriteStream('index.html'));
 
@@ -258,9 +258,39 @@ got(url.parse('http://todomvc.com'));
 got('https://todomvc.com', { rejectUnauthorized: false });
 
 got('/examples/angularjs', { baseUrl: 'http://todomvc.com' });
-got('http://todomvc.com', { headers: { foo: 'bar'} });
+got('http://todomvc.com', { headers: { foo: 'bar' } });
 got('http://todomvc.com', { cookieJar: new tough.CookieJar() });
 
+// Test extension
+got.extend({ method: 'POST' })('/example');
+got.extend({ method: 'POST' }).extend({ headers: {} }).stream('/example');
+
+// JSON options:
+// $ExpectType Promise<any>
+got.extend({ json: true })('/example').then(({ body }) => body);
+// $ExpectType Promise<any>
+got.extend({ baseUrl: 'https://localhost' }).extend({ json: true })('/example').then(({ body }) => body);
+// $ExpectType Promise<string>
+got.extend({})('/example').then(({ body }) => body);
+// Form options:
+// $ExpectType Promise<Buffer>
+got.extend({ form: true, encoding: null })('/example').then(({ body }) => body);
+// $ExpectType Promise<Buffer>
+got.extend({ form: true, encoding: null, body: {} })('/example').then(({ body }) => body);
+// $ExpectType Promise<string>
+got.extend({ form: true, encoding: 'utf8' })('/example').then(({ body }) => body);
+// $ExpectType Promise<string>
+got.extend({ form: true, encoding: 'utf8', body: {} })('/example').then(({ body }) => body);
+// Body options:
+// $ExpectType Promise<Buffer>
+got.extend({ encoding: null })('/example').then(({ body }) => body);
+// $ExpectType Promise<Buffer>
+got.extend({ encoding: null, body: '{}' })('/example').then(({ body }) => body);
+// $ExpectType Promise<string>
+got.extend({ encoding: 'utf8' })('/example').then(({ body }) => body);
+// $ExpectType Promise<string>
+got.extend({ encoding: 'utf8', body: '{}' })('/example').then(({ body }) => body);
+
 // Test retry options.
 got('http://todomvc.com', { retry: 2 });
 got('http://todomvc.com', {
@@ -284,7 +314,7 @@ got('http://todomvc.com', {
 got('http://todomvc.com', { throwHttpErrors: false });
 
 // Test timeout options.
-got('http://todomvc.com', {timeout: 1});
+got('http://todomvc.com', { timeout: 1 });
 got('http://todomvc.com', {
     timeout: {
         lookup: 1,
@@ -298,7 +328,7 @@ got('http://todomvc.com', {
 });
 
 // Test got.TimeoutError.
-got('http://todomvc.com', {timeout: 1}).catch((err) => err instanceof got.TimeoutError);
+got('http://todomvc.com', { timeout: 1 }).catch((err) => err instanceof got.TimeoutError);
 
 // Test hooks.
 got('example.com', {
diff --git a/types/got/index.d.ts b/types/got/index.d.ts
index a9f289b831..8fb6a71e63 100644
--- a/types/got/index.d.ts
+++ b/types/got/index.d.ts
@@ -4,8 +4,9 @@
 //                 Linus Unnebäck <https://github.com/LinusU>
 //                 Konstantin Ikonnikov <https://github.com/ikokostya>
 //                 Stijn Van Nieuwenhuyse <https://github.com/stijnvn>
+//                 Matthew Bull <https://github.com/wingsbob>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
-// TypeScript Version: 2.3
+// TypeScript Version: 2.8
 
 /// <reference types="node"/>
 
@@ -69,19 +70,7 @@ declare class StdError extends Error {
     response?: any;
 }
 
-declare const got: got.GotFn &
-    Record<'get' | 'post' | 'put' | 'patch' | 'head' | 'delete', got.GotFn> &
-    {
-        stream: got.GotStreamFn & Record<'get' | 'post' | 'put' | 'patch' | 'head' | 'delete', got.GotStreamFn>;
-        RequestError: typeof RequestError;
-        ReadError: typeof ReadError;
-        ParseError: typeof ParseError;
-        HTTPError: typeof HTTPError;
-        MaxRedirectsError: typeof MaxRedirectsError;
-        UnsupportedProtocolError: typeof UnsupportedProtocolError;
-        CancelError: typeof CancelError;
-        TimeoutError: typeof TimeoutError;
-    };
+declare const got: got.GotInstance;
 
 interface InternalRequestOptions extends https.RequestOptions {
     // Redeclare options with `any` type for allow specify types incompatible with http.RequestOptions.
@@ -99,6 +88,44 @@ declare namespace got {
         (url: GotUrl, options: GotBodyOptions<null>): GotPromise<Buffer>;
     }
 
+    interface GotJSONFn {
+        (url: GotUrl): GotPromise<any>;
+        (url: GotUrl, options: GotJSONOptions): GotPromise<any>;
+    }
+
+    interface GotFormFn<T extends string | null> {
+        (url: GotUrl): GotPromise<T extends null ? Buffer : string>;
+        (url: GotUrl, options: GotFormOptions<T>): GotPromise<T extends null ? Buffer : string>;
+    }
+
+    interface GotBodyFn<T extends string | null> {
+        (url: GotUrl): GotPromise<T extends null ? Buffer : string>;
+        (url: GotUrl, options: GotBodyOptions<T>): GotPromise<T extends null ? Buffer : string>;
+    }
+
+    type GotInstance<T = GotFn> = T &
+        Record<'get' | 'post' | 'put' | 'patch' | 'head' | 'delete', T> &
+    {
+        stream: GotStreamFn & Record<'get' | 'post' | 'put' | 'patch' | 'head' | 'delete', GotStreamFn>;
+        extend: GotExtend;
+        RequestError: typeof RequestError;
+        ReadError: typeof ReadError;
+        ParseError: typeof ParseError;
+        HTTPError: typeof HTTPError;
+        MaxRedirectsError: typeof MaxRedirectsError;
+        UnsupportedProtocolError: typeof UnsupportedProtocolError;
+        CancelError: typeof CancelError;
+        TimeoutError: typeof TimeoutError;
+    };
+
+    interface GotExtend {
+        (options: GotJSONOptions): GotInstance<GotJSONFn>;
+        (options: GotFormOptions<string>): GotInstance<GotFormFn<string>>;
+        (options: GotFormOptions<null>): GotInstance<GotFormFn<null>>;
+        (options: GotBodyOptions<string>): GotInstance<GotBodyFn<string>>;
+        (options: GotBodyOptions<null>): GotInstance<GotBodyFn<null>>;
+    }
+
     type GotStreamFn = (url: GotUrl, options?: GotOptions<string | null>) => GotEmitter & nodeStream.Duplex;
 
     type GotUrl = string | https.RequestOptions | Url | URL;