diff --git a/zerver/middleware.py b/zerver/middleware.py
index 02eae42946..2e25466574 100644
--- a/zerver/middleware.py
+++ b/zerver/middleware.py
@@ -373,7 +373,7 @@ class SessionHostDomainMiddleware(SessionMiddleware):
             if subdomain != Realm.SUBDOMAIN_FOR_ROOT_DOMAIN:
                 realm = get_realm(subdomain)
                 if (realm is None):
-                    return render(request, "zerver/invalid_realm.html")
+                    return render(request, "zerver/invalid_realm.html", status=404)
         """
         If request.session was modified, or if the configuration is to save the
         session every time, save the changes and set a session cookie or delete
diff --git a/zerver/tests/test_auth_backends.py b/zerver/tests/test_auth_backends.py
index 1d4af87127..01d568fb06 100644
--- a/zerver/tests/test_auth_backends.py
+++ b/zerver/tests/test_auth_backends.py
@@ -592,8 +592,9 @@ class SocialAuthBase(ZulipTestCase):
         account_data_dict = self.get_account_data_dict(email=self.email, name=self.name)
         result = self.social_auth_test(account_data_dict,
                                        subdomain='nonexistent')
-        self.assert_in_success_response(["There is no Zulip organization hosted at this subdomain."],
-                                        result)
+        self.assert_in_response("There is no Zulip organization hosted at this subdomain.",
+                                result)
+        self.assertEqual(result.status_code, 404)
 
     def test_user_cannot_log_into_wrong_subdomain(self) -> None:
         account_data_dict = self.get_account_data_dict(email=self.email, name=self.name)
@@ -1261,8 +1262,9 @@ class GoogleSubdomainLoginTest(GoogleOAuthTest):
         account_response = ResponseMock(200, account_data)
         result = self.google_oauth2_test(token_response, account_response,
                                          subdomain='nonexistent')
-        self.assert_in_success_response(["There is no Zulip organization hosted at this subdomain."],
-                                        result)
+        self.assert_in_response("There is no Zulip organization hosted at this subdomain.",
+                                result)
+        self.assertEqual(result.status_code, 404)
 
     def test_user_cannot_log_into_wrong_subdomain(self) -> None:
         token_response = ResponseMock(200, {'access_token': "unique_token"})
diff --git a/zerver/tests/test_docs.py b/zerver/tests/test_docs.py
index 8f5f3a5988..91c10ed039 100644
--- a/zerver/tests/test_docs.py
+++ b/zerver/tests/test_docs.py
@@ -355,7 +355,8 @@ class PlansPageTest(ZulipTestCase):
         self.assert_in_success_response(["Sign up now"], result)
         # Test non-existant domain
         result = self.client_get("/plans/", subdomain="moo")
-        self.assert_in_success_response(["does not exist"], result)
+        self.assertEqual(result.status_code, 404)
+        self.assert_in_response("does not exist", result)
         # Test valid domain, no login
         realm = get_realm("zulip")
         realm.plan_type = Realm.STANDARD_FREE
diff --git a/zerver/tests/test_signup.py b/zerver/tests/test_signup.py
index 23068b79f2..0b1458945a 100644
--- a/zerver/tests/test_signup.py
+++ b/zerver/tests/test_signup.py
@@ -320,9 +320,9 @@ class PasswordResetTest(ZulipTestCase):
             subdomain="invalid")
 
         # check the redirect link telling you to check mail for password reset link
-        self.assertEqual(result.status_code, 200)
-        self.assert_in_success_response(["There is no Zulip organization hosted at this subdomain."],
-                                        result)
+        self.assertEqual(result.status_code, 404)
+        self.assert_in_response("There is no Zulip organization hosted at this subdomain.",
+                                result)
 
         from django.core.mail import outbox
         self.assertEqual(len(outbox), 0)
@@ -440,7 +440,7 @@ class LoginTest(ZulipTestCase):
     def test_login_invalid_subdomain(self) -> None:
         result = self.login_with_return(self.example_email("hamlet"), "xxx",
                                         subdomain="invalid")
-        self.assertEqual(result.status_code, 200)
+        self.assertEqual(result.status_code, 404)
         self.assert_in_response("There is no Zulip organization hosted at this subdomain.", result)
         self.assertIsNone(get_session_dict_user(self.client.session))