diff --git a/components/Footer.tsx b/components/Footer.tsx
index 452d30b..7f90e08 100644
--- a/components/Footer.tsx
+++ b/components/Footer.tsx
@@ -23,7 +23,7 @@ export function Footer() {
     <footer>
       <div className="sponsors">
         <div className="sponsors__label">Yhteistyössä</div>
-        {sponsors.map(sponsor => (
+        {sponsors.map((sponsor) => (
           <SponsorLink key={sponsor.name} {...sponsor} />
         ))}
       </div>
diff --git a/components/InviteForm.tsx b/components/InviteForm.tsx
index 639a472..4d36538 100644
--- a/components/InviteForm.tsx
+++ b/components/InviteForm.tsx
@@ -12,7 +12,7 @@ export default class InviteForm extends React.Component {
     error: null,
   };
 
-  onSubmit = async e => {
+  onSubmit = async (e) => {
     e.preventDefault();
 
     this.setState({
@@ -35,11 +35,11 @@ export default class InviteForm extends React.Component {
     this.setState({ submitted: true, sending: false });
   };
 
-  handleError = err => {
+  handleError = (err) => {
     this.setState({ error: err, sending: false });
   };
 
-  onChange = e => {
+  onChange = (e) => {
     if (e.target.value === this.state.email) {
       return;
     }
diff --git a/components/Members.tsx b/components/Members.tsx
index 5389ac6..17130a0 100644
--- a/components/Members.tsx
+++ b/components/Members.tsx
@@ -20,7 +20,7 @@ export default class Members extends React.Component {
   }
 
   render() {
-    const members = this.state.members.map(member => {
+    const members = this.state.members.map((member) => {
       const src = `${member.avatar_url}&s=120`;
       return (
         <img className="member" key={member.avatar_url} src={src} alt="" />
diff --git a/components/feed-transformers.ts b/components/feed-transformers.ts
index 2d17f2e..c2916b0 100644
--- a/components/feed-transformers.ts
+++ b/components/feed-transformers.ts
@@ -13,7 +13,7 @@ const templateSettings = {
 
 export default {
   github(items) {
-    return items.filter(isVisibleGithubEvent).map(item => {
+    return items.filter(isVisibleGithubEvent).map((item) => {
       const template = lodashTemplate(
         githubEvent.parse(item).text,
         templateSettings,
@@ -49,7 +49,7 @@ export default {
     });
   },
   twitter(items) {
-    return items.map(item => {
+    return items.map((item) => {
       if (item.retweeted) {
         item = item.retweeted_status;
       }
diff --git a/components/membership/MembershipInfoForm.tsx b/components/membership/MembershipInfoForm.tsx
index 0da36f8..5034825 100644
--- a/components/membership/MembershipInfoForm.tsx
+++ b/components/membership/MembershipInfoForm.tsx
@@ -76,7 +76,7 @@ export default class MembershipInfoForm extends React.Component<Props, State> {
     }
   };
 
-  onChange = e => {
+  onChange = (e) => {
     const name = e.target.name;
     if (e.target.value === this.state[name]) {
       return;
@@ -88,7 +88,7 @@ export default class MembershipInfoForm extends React.Component<Props, State> {
         [name]: e.target.value,
       },
       pristineFields: this.state.pristineFields.filter(
-        fieldName => fieldName !== name
+        (fieldName) => fieldName !== name
       ),
       errors: [],
     });
@@ -97,7 +97,7 @@ export default class MembershipInfoForm extends React.Component<Props, State> {
   getDataErrors = () => {
     const foundErrors = [];
 
-    Object.keys(this.state.fields).forEach(fieldName => {
+    Object.keys(this.state.fields).forEach((fieldName) => {
       if (!this.state[fieldName]) {
         foundErrors.push({ field: fieldName, type: "missing" });
       }
@@ -123,10 +123,11 @@ export default class MembershipInfoForm extends React.Component<Props, State> {
     function getErrorMessage(err) {
       let feedbackText;
 
+      const fieldName = fieldNameTranslations[err.field].fi;
       if (err.type === "missing") {
-        feedbackText = `${fieldNameTranslations[err.field].fi} on pakollinen.`;
+        feedbackText = `${fieldName} on pakollinen.`;
       } else if (err.type === "invalid") {
-        feedbackText = `${fieldNameTranslations[err.field].fi} on virheellinen.`;
+        feedbackText = `${fieldName} on virheellinen.`;
       }
 
       return (
@@ -138,12 +139,12 @@ export default class MembershipInfoForm extends React.Component<Props, State> {
 
     /* generate error messages */
     const visibleErrors = inputErrors.filter(
-      error => this.state.pristineFields.indexOf(error.field) === -1
+      (error) => this.state.pristineFields.indexOf(error.field) === -1
     );
 
     const fieldsWithErrors = visibleErrors.map(({ field }) => field);
 
-    const inputFields = Object.keys(this.state.fields).map(fieldName => {
+    const inputFields = Object.keys(this.state.fields).map((fieldName) => {
       const inputClasses = classSet({
         input: true,
         "has-error": fieldsWithErrors.includes(fieldName),
diff --git a/package.json b/package.json
index 85f64f0..558c911 100644
--- a/package.json
+++ b/package.json
@@ -10,7 +10,7 @@
     "dev": "SERVER=http://localhost:9000/ ENV=development next",
     "prod": "ENV=production next build && next export",
     "lint": "eslint --ext .jsx --ext .js .",
-    "prettify": "prettier --write {components,pages,styles}/{*,**/*}.js*"
+    "prettify": "prettier --write components pages styles"
   },
   "dependencies": {
     "@zeit/next-css": "^1.0.1",
diff --git a/pages/_app.tsx b/pages/_app.tsx
index cbb2275..eead00c 100644
--- a/pages/_app.tsx
+++ b/pages/_app.tsx
@@ -1,5 +1,5 @@
-import React from 'react';
-import Head from 'next/head';
+import React from "react";
+import Head from "next/head";
 
 function MyApp({ Component, pageProps }) {
   return (
@@ -13,9 +13,9 @@ function MyApp({ Component, pageProps }) {
           name="keywords"
           content="ohjelmointi,frontend,open source,devaus,suomi,javascript,clojure,go,java,node.js,io.js,angular.js,web"
         />
-        <meta charSet="utf-8"/>
-        <meta name="viewport" content="width=device-width, initial-scale=1"/>
-        <meta name="apple-mobile-web-app-capable" content="yes"/>
+        <meta charSet="utf-8" />
+        <meta name="viewport" content="width=device-width, initial-scale=1" />
+        <meta name="apple-mobile-web-app-capable" content="yes" />
         <link
           rel="apple-touch-icon"
           sizes="180x180"
@@ -33,12 +33,12 @@ function MyApp({ Component, pageProps }) {
           sizes="16x16"
           href="/static/icons/favicon-16x16.png"
         />
-        <link rel="manifest" href="/static/icons/site.webmanifest"/>
-        <meta property="og:image" content="images/logo.png"/>
+        <link rel="manifest" href="/static/icons/site.webmanifest" />
+        <meta property="og:image" content="images/logo.png" />
       </Head>
       <Component {...pageProps} />
     </>
-  )
+  );
 }
 
 export default MyApp;