diff --git a/CHANGELOG.md b/CHANGELOG.md
index 137db0e..5d316bc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,11 @@ CHANGE LOG
 ==========
 
 
+## 5.1.1 (UPCOMING)
+
+* Add sensitive parameter annotations for authentication tokens
+
+
 ## 5.1.0 (06/05/2026)
 
 * Add PHP 8.5 support
diff --git a/composer.json b/composer.json
index e4ce9bb..3db83a2 100644
--- a/composer.json
+++ b/composer.json
@@ -28,7 +28,8 @@
         "php-http/httplug": "^2.4.1",
         "psr/http-client-implementation": "^1.0",
         "psr/http-factory-implementation": "^1.0",
-        "psr/http-message": "^1.1 || ^2.0"
+        "psr/http-message": "^1.1 || ^2.0",
+        "symfony/polyfill-php82": "^1.27"
     },
     "require-dev": {
         "bamarni/composer-bin-plugin": "^1.8.2",
diff --git a/src/Client.php b/src/Client.php
index 9f595f8..7898849 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -213,7 +213,7 @@ public function vpc(): Vpc
         return new Vpc($this);
     }
 
-    public function authenticate(string $token): void
+    public function authenticate(#[\SensitiveParameter] string $token): void
     {
         $this->getHttpClientBuilder()->addPlugin(new Authentication($token));
     }
diff --git a/src/HttpClient/Plugin/Authentication.php b/src/HttpClient/Plugin/Authentication.php
index 8cdc95f..7101e51 100644
--- a/src/HttpClient/Plugin/Authentication.php
+++ b/src/HttpClient/Plugin/Authentication.php
@@ -34,7 +34,7 @@ final class Authentication implements Plugin
      */
     private readonly string $header;
 
-    public function __construct(string $token)
+    public function __construct(#[\SensitiveParameter] string $token)
     {
         $this->header = \sprintf('Bearer %s', $token);
     }