diff --git a/src/AuthCommand.php b/src/AuthCommand.php
index ba74845..1ee6f6f 100644
--- a/src/AuthCommand.php
+++ b/src/AuthCommand.php
@@ -30,7 +30,7 @@ public function handle()
         $this->gen('SIMPLE_JWT_SECRET');
     }
 
-    public function gen($key, string $value = null)
+    public function gen($key, ?string $value = null)
     {
         if (empty(env($key))) {
             file_put_contents(BASE_PATH . '/.env', sprintf(PHP_EOL . '%s=%s', $key, $value ?? str_random(16)), FILE_APPEND);
diff --git a/src/Exception/UnauthorizedException.php b/src/Exception/UnauthorizedException.php
index f097677..8bcb168 100644
--- a/src/Exception/UnauthorizedException.php
+++ b/src/Exception/UnauthorizedException.php
@@ -20,7 +20,7 @@ class UnauthorizedException extends AuthException
 
     protected int $statusCode = 401;
 
-    public function __construct(string $message, AuthGuard $guard = null, Throwable $previous = null)
+    public function __construct(string $message, ?AuthGuard $guard = null, ?Throwable $previous = null)
     {
         parent::__construct($message, 401, $previous);
         $this->guard = $guard;
diff --git a/src/Guard/JwtGuard.php b/src/Guard/JwtGuard.php
index 7bcbaa3..df6f2a8 100644
--- a/src/Guard/JwtGuard.php
+++ b/src/Guard/JwtGuard.php
@@ -90,7 +90,7 @@ public function user(?string $token = null): ?Authenticatable
             if ($result instanceof UnauthorizedException) {
                 throw $result;
             }
-            return $result ?: null;
+            return $result ?? null;
         }
 
         try {
@@ -98,7 +98,7 @@ public function user(?string $token = null): ?Authenticatable
                 $jwt = $this->getJwtManager()->parse($token);
                 $uid = $jwt->getPayload()['uid'] ?? null;
                 $user = $uid ? $this->userProvider->retrieveByCredentials($uid) : null;
-                Context::set($key, $user ?: 0);
+                Context::set($key, $user ?? 0);
 
                 return $user;
             }
@@ -139,7 +139,7 @@ public function guest(?string $token = null): bool
      */
     public function refresh(?string $token = null): ?string
     {
-        $token = $token ?: $this->parseToken();
+        $token = $token ?? $this->parseToken();
 
         if ($token) {
             Context::set($this->resultKey($token), null);
@@ -158,7 +158,7 @@ public function refresh(?string $token = null): ?string
         return null;
     }
 
-    public function logout($token = null)
+    public function logout(?string $token = null)
     {
         if ($token = $token ?? $this->parseToken()) {
             Context::set($this->resultKey($token), null);
@@ -170,7 +170,7 @@ public function logout($token = null)
         return false;
     }
 
-    public function getPayload($token = null): ?array
+    public function getPayload(?string $token = null): ?array
     {
         if ($token = $token ?? $this->parseToken()) {
             return $this->getJwtManager()->justParse($token)->getPayload();
@@ -183,7 +183,7 @@ public function getJwtManager(): JWTManager
         return $this->jwtManager;
     }
 
-    public function id($token = null)
+    public function id(?string $token = null)
     {
         if ($token = $token ?? $this->parseToken()) {
             return $this->getJwtManager()->parse($token)->getPayload()['uid'];
diff --git a/src/Guard/SessionGuard.php b/src/Guard/SessionGuard.php
index bdb65a5..5e6747f 100644
--- a/src/Guard/SessionGuard.php
+++ b/src/Guard/SessionGuard.php
@@ -52,7 +52,7 @@ public function user(): ?Authenticatable
             if ($result instanceof \Throwable) {
                 throw $result;
             }
-            return $result ?: null;
+            return $result ?? null;
         }
 
         try {
diff --git a/src/Guard/SsoGuard.php b/src/Guard/SsoGuard.php
index 09187d9..5471553 100644
--- a/src/Guard/SsoGuard.php
+++ b/src/Guard/SsoGuard.php
@@ -46,9 +46,9 @@ public function getClients(): array
         return $this->config['clients'] ?? ['unknown'];
     }
 
-    public function login(Authenticatable $user, array $payload = [], string $client = null)
+    public function login(Authenticatable $user, array $payload = [], ?string $client = null)
     {
-        $client = $client ?: $this->getClients()[0]; // 需要至少配置一个客户端
+        $client = $client ?? $this->getClients()[0]; // 需要至少配置一个客户端
         $token = parent::login($user, $payload);
         $redisKey = str_replace('{uid}', (string) $user->getId(), $this->config['redis_key'] ?? 'u:token:{uid}');
 
@@ -64,12 +64,12 @@ public function login(Authenticatable $user, array $payload = [], string $client
         return $token;
     }
 
-    public function refresh(?string $token = null, string $client = null): ?string
+    public function refresh(?string $token = null, ?string $client = null): ?string
     {
         $token = parent::refresh($token);
 
         if ($token) {
-            $client = $client ?: $this->getClients()[0]; // 需要至少配置一个客户端
+            $client = $client ?? $this->getClients()[0]; // 需要至少配置一个客户端
             $redisKey = str_replace('{uid}', (string) $this->id($token), $this->config['redis_key'] ?? 'u:token:{uid}');
             $this->redis->hSet($redisKey, $client, $token);
         }