diff --git a/src/Authentication/NamiGuard.php b/src/Authentication/NamiGuard.php
index a956b1a..1a3ebc8 100644
--- a/src/Authentication/NamiGuard.php
+++ b/src/Authentication/NamiGuard.php
@@ -4,11 +4,14 @@ namespace Zoomyboy\LaravelNami\Authentication;
 
 use Illuminate\Auth\GuardHelpers;
 use Illuminate\Auth\SessionGuard;
+use Illuminate\Cache\Repository as CacheRepository;
 use Illuminate\Contracts\Auth\Authenticatable as AuthenticatableContract;
 use Illuminate\Contracts\Auth\Authenticatable;
 use Illuminate\Contracts\Auth\Guard;
+use Illuminate\Session\Store as SessionStore;
 use Illuminate\Support\Facades\Cache;
 use Illuminate\Support\Str;
+use Zoomyboy\LaravelNami\LoginException;
 use Zoomyboy\LaravelNami\Nami;
 use Zoomyboy\LaravelNami\NamiUser;
 
@@ -16,11 +19,18 @@ class NamiGuard {
 
     use GuardHelpers;
 
-    protected $cache;
-    protected $user;
-    protected $session;
+    protected CacheRepository $cache;
 
-    public function __construct($session, $cache) {
+    /**
+     * The currently authenticated user.
+     *
+     * @var ?NamiUser
+     */
+    protected $user;
+
+    protected SessionStore $session;
+
+    public function __construct(SessionStore $session, CacheRepository $cache) {
         $this->session = $session;
         $this->cache = $cache;
     }
@@ -28,14 +38,15 @@ class NamiGuard {
     /**
      * Set the current user.
      *
-     * @param  \Illuminate\Contracts\Auth\Authenticatable  $user
+     * @param  NamiUser|null $user
      * @return void
      */
-    public function setUser(NamiUser $user) {
+    public function setUser(?NamiUser $user): void
+    {
         $this->user = $user;
     }
 
-    public function user()
+    public function user(): ?NamiUser
     {
         if (! is_null($this->user)) {
             return $this->user;
@@ -44,42 +55,60 @@ class NamiGuard {
         $cache = $this->resolveCache();
 
         if (!$cache) {
-            return;
+            return null;
         }
 
         return NamiUser::fromPayload($cache);
     }
 
-    public function attempt(array $credentials = [], $remember = false) {
-        $api = Nami::login($credentials['mglnr'], $credentials['password']);
+    /**
+     * @param array<string, string> $credentials
+     * @param bool $remember
+     */
+    public function attempt(array $credentials = [], bool $remember = false): bool
+    {
+        try {
+            $api = Nami::login($credentials['mglnr'], $credentials['password']);
 
-        $payload = [
-            'credentials' => $credentials
-        ];
+            $payload = [
+                'credentials' => $credentials
+            ];
 
-        $this->setUser(NamiUser::fromPayload($payload));
-        $key = $this->newCacheKey();
-        Cache::forever("namiauth-{$key}", $payload);
-        $this->updateSession($key);
+            $this->setUser(NamiUser::fromPayload($payload));
+            $key = $this->newCacheKey();
+            Cache::forever("namiauth-{$key}", $payload);
+            $this->updateSession($key);
 
-        return true;
+            return true;
+        } catch (LoginException $e) {
+            return false;
+        }
     }
 
-    protected function updateSession($data)
+    protected function updateSession(string $data): void
     {
         $this->session->put($this->getName(), $data);
         $this->session->migrate(true);
     }
 
-    public function getName() {
+    public function getName(): string
+    {
         return 'auth_key';
     }
 
-    private function resolveCache() {
+    public function logout(): void
+    {
+        $this->session->forget($this->getName());
+        $this->setUser(null);
+    }
+
+    private function resolveCache(): ?string
+    {
         return $this->cache->get('namiauth-'.$this->session->get($this->getName()));
     }
 
-    private function newCacheKey() {
+    private function newCacheKey(): string
+    {
         return Str::random(16);
     }