diff --git a/.eslintrc.js b/.eslintrc.js
index 5336804..b8bad43 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -1,12 +1,23 @@
 module.exports = {
-  parserOptions: {
-    project: "./tsconfig.json"
-  },
   extends: [
     "plugin:@typescript-eslint/recommended",
     "airbnb-typescript",
     "next",
-    "next/core-web-vitals"
+    "next/core-web-vitals",
+  ],
+  parser: '@typescript-eslint/parser',
+  parserOptions: {
+    tsconfigRootDir: __dirname,
+    project: './tsconfig.json',
+  },
+  plugins: ['@typescript-eslint'],
+  overrides: [
+    {
+      files: ['*.js'],
+      rules: {
+        '@typescript-eslint/no-var-requires': 'off',
+      },
+    },
   ],
   rules: {
     "max-len": [
@@ -17,13 +28,8 @@ module.exports = {
       "error",
       "double"
     ],
-    "import/prefer-default-export": "warn",
-    "react/jsx-props-no-spreading": "off",
-    "react/prop-types": "off",
     "react/jsx-one-expression-per-line": "off",
-    "eslintreact/jsx-one-expression-per-line": "off",
     // Temp
-    "import/no-cycle": "warn",
     "react/no-array-index-key": "warn",
     "jsx-a11y/label-has-associated-control": "off",
     "jsx-a11y/click-events-have-key-events": "off",
diff --git a/next.config.js b/next.config.js
index 9db006e..24890a1 100644
--- a/next.config.js
+++ b/next.config.js
@@ -10,5 +10,5 @@ module.exports = withBundleAnalyzer({
       "static.sahkoinsinoorikilta.fi",
       "api.dev.sahkoinsinoorikilta.fi",
     ],
-  }
+  },
 });
diff --git a/package-lock.json b/package-lock.json
index 7e45f35..9e13636 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -42,6 +42,7 @@
         "@types/shortid": "^0.0.29",
         "@types/styled-components": "^5.1.12",
         "@typescript-eslint/eslint-plugin": "^4.29.2",
+        "@typescript-eslint/parser": "^4.29.2",
         "babel-plugin-styled-components": "^1.13.2",
         "eslint": "^7.32.0",
         "eslint-config-airbnb": "^18.2.1",
diff --git a/package.json b/package.json
index 37c6503..7454ea5 100644
--- a/package.json
+++ b/package.json
@@ -42,6 +42,7 @@
     "@types/shortid": "^0.0.29",
     "@types/styled-components": "^5.1.12",
     "@typescript-eslint/eslint-plugin": "^4.29.2",
+    "@typescript-eslint/parser": "^4.29.2",
     "babel-plugin-styled-components": "^1.13.2",
     "eslint": "^7.32.0",
     "eslint-config-airbnb": "^18.2.1",
diff --git a/src/components/Navigation.tsx b/src/components/Navigation.tsx
index 144a69c..cfb1925 100644
--- a/src/components/Navigation.tsx
+++ b/src/components/Navigation.tsx
@@ -6,7 +6,7 @@ import Icon, { IconType } from "./Icon";
 import NavbarDropdownLink from "./NavbarDropdownLink";
 import NavbarChildLink from "./NavbarChildLink";
 
-export const renderNavigationItems = (mobile = false) => (
+export const renderNavigationItems = (mobile = false): JSX.Element => (
   <>
     <NavbarDropdownLink to="/kilta" text="Kilta ›" exploded={mobile}>
       <NavbarChildLink to="/kilta/toiminta">Toiminta</NavbarChildLink>
diff --git a/src/components/Widgets/SignupQuestionsWidget/TypeWidget.tsx b/src/components/Widgets/SignupQuestionsWidget/TypeWidget.tsx
index c4d1e53..3541360 100644
--- a/src/components/Widgets/SignupQuestionsWidget/TypeWidget.tsx
+++ b/src/components/Widgets/SignupQuestionsWidget/TypeWidget.tsx
@@ -7,15 +7,15 @@ interface TypeWidgetProps {
 }
 
 class TypeWidget extends React.Component<TypeWidgetProps> {
-  handleTypeChange = (questions: Question[], index: number) => (event) => {
+  handleTypeChange = (questions: Question[], index: number): React.ChangeEventHandler<HTMLSelectElement> => (event) => {
     const { onChange } = this.props;
-    const val = event.target.value;
+    const val = event.target.value as Question["type"];
     // eslint-disable-next-line no-param-reassign
     questions[index].type = val;
     onChange(questions);
   };
 
-  render() {
+  render(): JSX.Element {
     const { inputProps } = this.props;
     const { type, questions, index } = inputProps;
     const options = optionTypes.map((t) => (
diff --git a/src/pages/_document.tsx b/src/pages/_document.tsx
index 46d1dcc..b45cf1b 100644
--- a/src/pages/_document.tsx
+++ b/src/pages/_document.tsx
@@ -1,13 +1,13 @@
 import React from "react";
 import Document, {
-  Html, Head, Main, NextScript, DocumentContext,
+  Html, Head, Main, NextScript, DocumentContext, DocumentInitialProps,
 } from "next/document";
 import { ServerStyleSheet } from "styled-components";
 import Favicons from "@components/Favicons";
 import HTMLLogo from "@components/HTMLLogo";
 
 export default class MyDocument extends Document<{ styleTags: unknown }> {
-  static async getInitialProps(ctx: DocumentContext) {
+  static async getInitialProps(ctx: DocumentContext): Promise<DocumentInitialProps> {
     const sheet = new ServerStyleSheet();
     const originalRenderPage = ctx.renderPage;
     try {
diff --git a/tsconfig.json b/tsconfig.json
index 91f6568..50ff755 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -57,7 +57,10 @@
   "include": [
     "./src/**/*",
     "./types/**/*",
-    "./tests/testcafe/**/*"
+    "./tests/testcafe/**/*",
+    "next-sitemap.js",
+    "next.config.js",
+    ".eslintrc.js"
   ],
   "exclude": [
     "node_modules"