diff --git a/Plugin/SwitchSameSite.php b/Plugin/SwitchSameSite.php
index 40eb20d..e98cd0f 100644
--- a/Plugin/SwitchSameSite.php
+++ b/Plugin/SwitchSameSite.php
@@ -60,7 +60,7 @@ public function beforeSetPublicCookie(
         PhpCookieManager $subject,
         $name,
         $value,
-        PublicCookieMetadata $metadata = null
+        ?PublicCookieMetadata $metadata = null
     ) {
         if ($this->isAffectedKeys($name)) {
             $agent = $this->header->getHttpUserAgent();
diff --git a/composer.json b/composer.json
index 3c41371..4232b74 100644
--- a/composer.json
+++ b/composer.json
@@ -16,7 +16,7 @@
         }
     ],
     "require": {
-        "php": "~7.4.0||~8.1.0||~8.2.0||~8.3.0",
+        "php": "~7.4.0||~8.1.0||~8.2.0||~8.3.0||~8.4.0",
         "magento/framework": "~102.0.6-p1||~103.0.1",
         "lib-libxml": "*"
     },