diff --git a/src/controllers/MagicLoginController.php b/src/controllers/MagicLoginController.php
index 150ebaf..999cfc6 100755
--- a/src/controllers/MagicLoginController.php
+++ b/src/controllers/MagicLoginController.php
@@ -11,10 +11,11 @@
 namespace creode\magiclogin\controllers;
 
 use Craft;
+use DateTime;
 use craft\elements\User;
 use craft\web\Controller;
 use creode\magiclogin\MagicLogin;
-use DateTime;
+use yii\web\NotFoundHttpException;
 
 /**
  * MagicLogin Controller
@@ -162,6 +163,11 @@ public function actionRegisterForm()
             $this->redirect($generalConfig->postLoginRedirect);
         }
 
+        $userConfig = Craft::$app->getProjectConfig()->get('users') ?? [];
+        if (! $userConfig['allowPublicRegistration']) {
+            throw new NotFoundHttpException();
+        }
+
         return $this->renderTemplate('magic-login/_register-form');
     }
 
@@ -181,6 +187,11 @@ public function actionRegister()
             )
         );
 
+        $userSettings = Craft::$app->getProjectConfig()->get('users');
+        if (!$userSettings['allowPublicRegistration']) {
+            throw new NotFoundHttpException();
+        }
+
         if (Craft::$app->getUser()->getIdentity()) {
             $generalConfig = Craft::$app->getConfig()->getGeneral();
             $this->setSuccessFlash(\Craft::t('magic-login', 'You are already logged in.'));
@@ -191,6 +202,12 @@ public function actionRegister()
             ->getRequest()
             ->getRequiredParam('email');
 
+        $generalConfig = Craft::$app->getConfig()->getGeneral();
+        if (! $generalConfig->useEmailAsUsername) {
+            $this->setFailFlash(\Craft::t('magic-login', 'Please enter a valid username.'));
+            return;
+        }
+
         if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
             // TODO: Maybe set this to be configurable in future.
             $this->setFailFlash(\Craft::t('magic-login', 'Please enter a valid email address.'));
diff --git a/test-config/general.php b/test-config/general.php
index 6b398e9..9e1affa 100644
--- a/test-config/general.php
+++ b/test-config/general.php
@@ -2,4 +2,5 @@
 
 return [
 	'postLoginRedirect' => '',
+	'useEmailAsUsername' => true,
 ];
diff --git a/tests/_craft/config/general.php b/tests/_craft/config/general.php
index 8684f17..c7774f1 100644
--- a/tests/_craft/config/general.php
+++ b/tests/_craft/config/general.php
@@ -8,4 +8,5 @@
 	'requireUserAgentAndIpForSession' => false,
 	'securityKey' => App::env('SECURITY_KEY'),
 	'enableCsrfProtection' => false,
+	'useEmailAsUsername' => true,
 ];
diff --git a/tests/functional/LoginFormTest.php b/tests/functional/LoginFormTest.php
index 5382479..eccae5b 100644
--- a/tests/functional/LoginFormTest.php
+++ b/tests/functional/LoginFormTest.php
@@ -100,7 +100,7 @@ public function testUnregisteredUserSignup()
         $this->tester->submitForm(
             '#magic-login-form',
             [
-                'email' => 'test@example.com',
+                'email' => 'test-2@example.com',
             ],
             'submitButton'
         );
diff --git a/tests/functional/RegistrationFormTest.php b/tests/functional/RegistrationFormTest.php
index 80a5d67..05c00ad 100644
--- a/tests/functional/RegistrationFormTest.php
+++ b/tests/functional/RegistrationFormTest.php
@@ -365,6 +365,37 @@ public function testWhenRegistrationErrorOccursUserIsNotCreated()
         $this->assertEquals($userCount, count(User::find()->all()));
     }
 
+    /**
+     * Test that we return a 404, not the user registration page when public registration is disabled.
+     */
+    public function testWhenPublicRegistrationDisabledUserCannotRegister()
+    {
+        $userSettings = Craft::$app->getProjectConfig()->get('users') ?? [];
+        $userSettings['allowPublicRegistration'] = false;
+        Craft::$app->projectConfig->set('users', $userSettings);
+
+        $this->tester->amOnPage('/magic-login/register');
+        $this->tester->seeResponseCodeIs(404);
+    }
+
+    public function testWhenPublicRegistrationDisabledUserCannotRegisterWithMagicLink()
+    {
+        $this->tester->amOnPage('/magic-login/register');
+
+        $userSettings = Craft::$app->getProjectConfig()->get('users') ?? [];
+        $userSettings['allowPublicRegistration'] = false;
+
+        Craft::$app->projectConfig->set('users', $userSettings);
+        $this->tester->submitForm(
+            '#magic-login-register',
+            [
+                'email' => 'creode-test@example.com',
+            ],
+        );
+
+        $this->tester->seeResponseCodeIs(404);
+    }
+
     /**
      * Tests that when a user is successfully registered the magic
      * login group is attached.
diff --git a/tests/functional/SignupFormCest.php b/tests/functional/SignupFormCest.php
new file mode 100644
index 0000000..c645436
--- /dev/null
+++ b/tests/functional/SignupFormCest.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace creode\magiclogintests\acceptance;
+
+use Craft;
+use FunctionalTester;
+
+class SignupFormCest
+{
+    public function _before(FunctionalTester $I)
+    {
+        // Ensure useEmailAsUsername is set to true.
+        $generalConfig = Craft::$app->getConfig()->getGeneral();
+        $generalConfig->useEmailAsUsername = false;
+    }
+
+    public function testSignupFormWithoutRequiredUsername(FunctionalTester $I)
+    {
+        $I->amOnPage('/magic-login/register');
+        
+        // Attempt to submit the form with only an email address
+        $I->fillField('email', 'test@example.com');
+        $I->click('Submit');
+
+        // Expect error messages and no redirection
+        $I->dontSeeInCurrentUrl('/confirmation');
+        $I->see('Please enter a valid username'); // Adjust according to the actual error message expected
+    }
+
+    public function _after(FunctionalTester $I)
+    {
+        // Reset useEmailAsUsername to true
+        $generalConfig = Craft::$app->getConfig()->getGeneral();
+        $generalConfig->useEmailAsUsername = true;
+    }
+}