diff --git a/app/components/Auth.js b/app/components/Auth.js
index 268dae30..894ffb6c 100644
--- a/app/components/Auth.js
+++ b/app/components/Auth.js
@@ -8,6 +8,7 @@ import UsersStore from 'stores/UsersStore';
 import CollectionsStore from 'stores/CollectionsStore';
 import IntegrationsStore from 'stores/IntegrationsStore';
 import LoadingIndicator from 'components/LoadingIndicator';
+import { isCustomSubdomain } from 'shared/utils/domains';
 
 type Props = {
   auth: AuthStore,
@@ -26,13 +27,12 @@ const Auth = observer(({ auth, children }: Props) => {
     }
 
     // If we're authenticated but viewing a subdomain that doesn't match the
-    // authenticated team then kick the user to the teams subdomain.
-    // www is a special case, as always
+    // currently authenticated team then kick the user to the teams subdomain.
     if (
       process.env.SUBDOMAINS_ENABLED &&
       team.subdomain &&
-      !hostname.startsWith(`${team.subdomain}.`) &&
-      !hostname.startsWith('www.')
+      isCustomSubdomain(hostname) &&
+      !hostname.startsWith(`${team.subdomain}.`)
     ) {
       window.location.href = `${team.url}${window.location.pathname}`;
       return <LoadingIndicator />;
diff --git a/server/routes.js b/server/routes.js
index 926f5541..b0378c4d 100644
--- a/server/routes.js
+++ b/server/routes.js
@@ -8,6 +8,7 @@ import serve from 'koa-static';
 import parseDomain from 'parse-domain';
 import apexRedirect from './middlewares/apexRedirect';
 import renderpage from './utils/renderpage';
+import { isCustomSubdomain } from '../shared/utils/domains';
 import { robotsResponse } from './utils/robots';
 import { NotFoundError } from './errors';
 import { Team } from './models';
@@ -67,8 +68,6 @@ router.get('/changelog', async ctx => {
 router.get('/', async ctx => {
   const lastSignedIn = ctx.cookies.get('lastSignedIn');
   const accessToken = ctx.cookies.get('accessToken');
-  const domain = parseDomain(ctx.request.hostname);
-  const subdomain = domain ? domain.subdomain : undefined;
 
   // Because we render both the signed in and signed out views depending
   // on a cookie it's important that the browser does not render from cache.
@@ -82,11 +81,16 @@ router.get('/', async ctx => {
 
   // If we're on a custom subdomain then we display a slightly different signed
   // out view that includes the teams basic information.
-  if (subdomain && subdomain !== 'www') {
+  if (
+    process.env.SUBDOMAINS_ENABLED === 'true' &&
+    isCustomSubdomain(ctx.request.hostname)
+  ) {
+    const domain = parseDomain(ctx.request.hostname);
+    const subdomain = domain ? domain.subdomain : undefined;
     const team = await Team.find({
       where: { subdomain },
     });
-    if (team && process.env.SUBDOMAINS_ENABLED === 'true') {
+    if (team) {
       return renderpage(
         ctx,
         <SubdomainSignin
diff --git a/shared/utils/domains.js b/shared/utils/domains.js
index c9c3629f..7609399f 100644
--- a/shared/utils/domains.js
+++ b/shared/utils/domains.js
@@ -9,6 +9,13 @@ export function stripSubdomain(hostname: string) {
   return parsed.domain;
 }
 
+export function isCustomSubdomain(hostname: string) {
+  const parsed = parseDomain(hostname);
+  if (!parsed) return false;
+  if (!parsed.subdomain || parsed.subdomain === 'www') return false;
+  return true;
+}
+
 export const RESERVED_SUBDOMAINS = [
   'about',
   'account',
diff --git a/shared/utils/domains.test.js b/shared/utils/domains.test.js
index c0556f47..b3f9d845 100644
--- a/shared/utils/domains.test.js
+++ b/shared/utils/domains.test.js
@@ -1,5 +1,5 @@
 /* eslint-disable flowtype/require-valid-file-annotation */
-import { stripSubdomain } from './domains';
+import { stripSubdomain, isCustomSubdomain } from './domains';
 
 describe('#stripSubdomain', () => {
   test('to work with localhost', () => {
@@ -15,3 +15,22 @@ describe('#stripSubdomain', () => {
     expect(stripSubdomain('test.example.com:3000')).toBe('example.com');
   });
 });
+
+describe('#isCustomSubdomain', () => {
+  test('to work with localhost', () => {
+    expect(isCustomSubdomain('localhost')).toBe(false);
+  });
+  test('to return false for domains without a subdomain', () => {
+    expect(isCustomSubdomain('example')).toBe(false);
+    expect(isCustomSubdomain('example.com')).toBe(false);
+    expect(isCustomSubdomain('example.org:3000')).toBe(false);
+  });
+  test('to return false for www', () => {
+    expect(isCustomSubdomain('www.example.com')).toBe(false);
+    expect(isCustomSubdomain('www.example.com:3000')).toBe(false);
+  });
+  test('to return true for subdomains', () => {
+    expect(isCustomSubdomain('test.example.com')).toBe(true);
+    expect(isCustomSubdomain('test.example.com:3000')).toBe(true);
+  });
+});