diff --git a/.vscode/settings.json b/.vscode/settings.json
index 0989be2..35116db 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -11,6 +11,7 @@
     128
   ],
 
+
   // ---------------------------------------------------------------------------------------------------------------------------
   // Files
   // ---------------------------------------------------------------------------------------------------------------------------
@@ -32,12 +33,28 @@
   "typescript.tsdk": "node_modules/typescript/lib",
 
 
+  // ---------------------------------------------------------------------------------------------------------------------------
+  // Extensions
+  // ---------------------------------------------------------------------------------------------------------------------------
+  // ESLint
+  "eslint.autoFixOnSave": true,
+  "eslint.validate": [
+    { "language": "javascript", "autoFix": true },
+    { "language": "javascriptreact", "autoFix": true },
+    { "language": "typescript", "autoFix": true },
+    { "language": "typescriptreact", "autoFix": true }
+  ],
+
+
   // ---------------------------------------------------------------------------------------------------------------------------
   // Language Setings
   // ---------------------------------------------------------------------------------------------------------------------------
   "[javascript]": {
     "editor.formatOnSave": true
   },
+  "[javascriptreact]": {
+    "editor.formatOnSave": true
+  },
   "[typescript]": {
     "editor.formatOnSave": true
   },
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3629dcd..20eb1d7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,9 @@
 # Changelog
+## 1.0.1 (2019-12-13)
+- Fix setting headers after sending #10 - [@jagaapple](https://github.com/jagaapple)
+- Improve development environment
+  - Enable automatic code formatting for VS Code #8 - [@jagaapple](https://github.com/jagaapple)
+
 ## 1.0.0 (2019-12-04)
 - Initial public release - [@jagaapple](https://github.com/jagaapple)
 
diff --git a/example/pages/redirector.tsx b/example/pages/redirector.tsx
new file mode 100644
index 0000000..5560b31
--- /dev/null
+++ b/example/pages/redirector.tsx
@@ -0,0 +1,19 @@
+import { ServerResponse } from "http";
+import { NextPage } from "next";
+
+const moveToTop = (res: ServerResponse) => {
+  res.writeHead(302, { Location: "/" });
+  res.end();
+};
+
+const Page: NextPage = () => null;
+
+Page.getInitialProps = async ({ res }) => {
+  if (res == undefined) return {};
+
+  moveToTop(res);
+
+  return {};
+};
+
+export default Page;
diff --git a/package-lock.json b/package-lock.json
index 57d625f..abac5a5 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "next-secure-headers",
-  "version": "1.0.0",
+  "version": "1.0.1",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/package.json b/package.json
index 26af595..2d8c72c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "next-secure-headers",
-  "version": "1.0.0",
+  "version": "1.0.1",
   "description": "Sets secure response headers for Next.js.",
   "keywords": [
     "Next.js",
diff --git a/src/index.spec.ts b/src/index.spec.ts
index 8437ceb..eed0e94 100644
--- a/src/index.spec.ts
+++ b/src/index.spec.ts
@@ -1,7 +1,7 @@
 import * as React from "react";
 
 import * as rules from "./rules";
-import { default as withSecureHeaders, createHeadersObject } from "./index";
+import { createHeadersObject, default as withSecureHeaders } from "./index";
 
 describe("createHeadersObject", () => {
   let contentSecurityPolicyHeaderCreatorSpy: jest.SpyInstance<
@@ -188,5 +188,28 @@ describe("withSecureHeaders", () => {
         await expect(ComponentWithSecureHeaders.getInitialProps!(dummyContext)).resolves.toEqual(dummyInitialProps);
       });
     });
+
+    context('when "headersSent" property of "res" is true', () => {
+      it('should not call "context.ctx.res.setHeader()"', async () => {
+        const DummyComponent = () => React.createElement("div");
+        const ComponentWithSecureHeaders = withSecureHeaders()(DummyComponent);
+
+        const resSetHeeaderSpy = jest.fn();
+        const dummyContext: any = { ctx: { res: { setHeader: resSetHeeaderSpy, headersSent: true } } };
+        await ComponentWithSecureHeaders.getInitialProps!(dummyContext);
+
+        expect(resSetHeeaderSpy).not.toBeCalled();
+      });
+
+      it('should return the returned value from "getInitialProps"', async () => {
+        const DummyComponent = () => React.createElement("div");
+        const dummyInitialProps = { dummy: "dummy" };
+        DummyComponent.getInitialProps = async () => dummyInitialProps;
+        const ComponentWithSecureHeaders = withSecureHeaders()(DummyComponent);
+
+        const dummyContext: any = { ctx: { res: { setHeader: jest.fn(), headersSent: true } } };
+        await expect(ComponentWithSecureHeaders.getInitialProps!(dummyContext)).resolves.toEqual(dummyInitialProps);
+      });
+    });
   });
 });
diff --git a/src/index.ts b/src/index.ts
index f14cda4..647066f 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -90,6 +90,7 @@ export default (options: Options = {}) => (ChildComponent: NextComponent) => {
     const initialProps = (await ChildComponent.getInitialProps?.(context)) ?? {};
     const res = context.res ?? context.ctx?.res;
     if (res == undefined) return initialProps;
+    if (res.headersSent) return initialProps;
 
     const headers = createHeadersObject(options);
     Object.entries(headers).forEach(([name, value]) => res.setHeader(name, value));