diff --git a/README.md b/README.md
index 95a37684..3bb1c9c5 100644
--- a/README.md
+++ b/README.md
@@ -228,7 +228,6 @@ Providing an alternative way to decide which requests should be proxied; In case
     if (should_add_something) path += "something";
     return path;
   }
-
   ```
 
 - **option.router**: object/function, re-target `option.target` for specific requests.
@@ -243,11 +242,20 @@ Providing an alternative way to decide which requests should be proxied; In case
       '/rest'                      : 'http://localhost:8004'   // path only
   }
 
-  // Custom router function
+  // Custom router function (string target)
   router: function(req) {
       return 'http://localhost:8004';
   }
 
+  // Custom router function (target object)
+  router: function(req) {
+      return {
+          protocol: 'https:', // The : is required
+          host: 'localhost',
+          port: 8004
+      };
+  }
+
   // Asynchronous router function which returns promise
   router: async function(req) {
       const url = await doSomeIO();
diff --git a/src/types.ts b/src/types.ts
index d735606c..e845cf81 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -18,14 +18,14 @@ export interface Options extends httpProxy.ServerOptions {
     | ((path: string, req: Request) => string)
     | ((path: string, req: Request) => Promise<string>);
   router?:
-    | { [hostOrPath: string]: string }
-    | ((req: Request) => string)
-    | ((req: Request) => Promise<string>);
+    | { [hostOrPath: string]: httpProxy.ServerOptions['target'] }
+    | ((req: Request) => httpProxy.ServerOptions['target'])
+    | ((req: Request) => Promise<httpProxy.ServerOptions['target']>);
   logLevel?: 'debug' | 'info' | 'warn' | 'error' | 'silent';
   logProvider?(provider: LogProvider): LogProvider;
 
   onError?(err: Error, req: Request, res: Response): void;
-  onProxyRes?(proxyRes: http.ServerResponse, req: Request, res: Response): void;
+  onProxyRes?(proxyRes: http.IncomingMessage, req: Request, res: Response): void;
   onProxyReq?(proxyReq: http.ClientRequest, req: Request, res: Response): void;
   onProxyReqWs?(
     proxyReq: http.ClientRequest,
diff --git a/test/e2e/router.spec.ts b/test/e2e/router.spec.ts
index ee25c995..bca9cae1 100644
--- a/test/e2e/router.spec.ts
+++ b/test/e2e/router.spec.ts
@@ -1,6 +1,10 @@
 import { createProxyMiddleware, createApp, createAppWithPath } from './_utils';
 import * as request from 'supertest';
-import { getLocal, Mockttp } from 'mockttp';
+import { getLocal, generateCACertificate, Mockttp } from 'mockttp';
+
+const untrustedCACert = generateCACertificate({ bits: 1024 });
+
+process.env.NODE_TLS_REJECT_UNAUTHORIZED = '0';
 
 describe('E2E router', () => {
   let targetServerA: Mockttp;
@@ -8,17 +12,33 @@ describe('E2E router', () => {
   let targetServerC: Mockttp;
 
   beforeEach(async () => {
-    targetServerA = getLocal();
-    targetServerB = getLocal();
-    targetServerC = getLocal();
+    targetServerA = getLocal({ https: await untrustedCACert });
+    targetServerB = getLocal({ https: await untrustedCACert });
+    targetServerC = getLocal({ https: await untrustedCACert });
+
+    await targetServerA
+      .anyRequest()
+      .thenPassThrough({ ignoreHostCertificateErrors: ['localhost'] });
+    await targetServerB
+      .anyRequest()
+      .thenPassThrough({ ignoreHostCertificateErrors: ['localhost'] });
+    await targetServerC
+      .anyRequest()
+      .thenPassThrough({ ignoreHostCertificateErrors: ['localhost'] });
+
+    await targetServerA
+      .anyRequest()
+      .thenCallback(({ protocol }) => ({ body: protocol === 'https' ? 'A' : 'NOT HTTPS A' }));
+    await targetServerB
+      .anyRequest()
+      .thenCallback(({ protocol }) => ({ body: protocol === 'https' ? 'B' : 'NOT HTTPS B' }));
+    await targetServerC
+      .anyRequest()
+      .thenCallback(({ protocol }) => ({ body: protocol === 'https' ? 'C' : 'NOT HTTPS C' }));
 
     await targetServerA.start(6001);
     await targetServerB.start(6002);
     await targetServerC.start(6003);
-
-    targetServerA.get().thenReply(200, 'A');
-    targetServerB.get().thenReply(200, 'B');
-    targetServerC.get().thenReply(200, 'C');
   });
 
   afterEach(async () => {
@@ -27,13 +47,50 @@ describe('E2E router', () => {
     await targetServerC.stop();
   });
 
-  describe('router with proxyTable', () => {
-    it('should proxy to: "localhost:6003/api"', async () => {
+  describe('router with req', () => {
+    it('should work with a string', async () => {
+      const app = createApp(
+        createProxyMiddleware({
+          target: 'https://localhost:6001',
+          secure: false,
+          changeOrigin: true,
+          router(req) {
+            return 'https://localhost:6003';
+          }
+        })
+      );
+
+      const agent = request(app);
+      const response = await agent.get('/api').expect(200);
+      expect(response.text).toBe('C');
+    });
+
+    it('should work with an object', async () => {
       const app = createApp(
         createProxyMiddleware({
-          target: `http://localhost:6001`,
+          target: 'https://localhost:6001',
+          secure: false,
+          changeOrigin: true,
           router(req) {
-            return 'http://localhost:6003';
+            return { host: 'localhost', port: 6003, protocol: 'https:' };
+          }
+        })
+      );
+      const agent = request(app);
+      const response = await agent.get('/api').expect(200);
+      expect(response.text).toBe('C');
+    });
+
+    it('should work with an async callback', async () => {
+      const app = createApp(
+        createProxyMiddleware({
+          target: 'https://localhost:6001',
+          secure: false,
+          changeOrigin: true,
+          router: async req => {
+            return new Promise(resolve =>
+              resolve({ host: 'localhost', port: 6003, protocol: 'https:' })
+            );
           }
         })
       );
@@ -42,6 +99,25 @@ describe('E2E router', () => {
       const response = await agent.get('/api').expect(200);
       expect(response.text).toBe('C');
     });
+
+    it('missing a : will cause it to use http', async () => {
+      const app = createApp(
+        createProxyMiddleware({
+          target: 'https://localhost:6001',
+          secure: false,
+          changeOrigin: true,
+          router: async req => {
+            return new Promise(resolve =>
+              resolve({ host: 'localhost', port: 6003, protocol: 'https' })
+            );
+          }
+        })
+      );
+
+      const agent = request(app);
+      const response = await agent.get('/api').expect(200);
+      expect(response.text).toBe('NOT HTTPS C');
+    });
   });
 
   describe('router with proxyTable', () => {
@@ -51,11 +127,13 @@ describe('E2E router', () => {
       const app = createAppWithPath(
         '/',
         createProxyMiddleware({
-          target: 'http://localhost:6001',
+          target: 'https://localhost:6001',
+          secure: false,
+          changeOrigin: true,
           router: {
-            'alpha.localhost:6000': 'http://localhost:6001',
-            'beta.localhost:6000': 'http://localhost:6002',
-            'localhost:6000/api': 'http://localhost:6003'
+            'alpha.localhost:6000': 'https://localhost:6001',
+            'beta.localhost:6000': 'https://localhost:6002',
+            'localhost:6000/api': 'https://localhost:6003'
           }
         })
       );