diff --git a/src/CTConfig.php b/src/CTConfig.php
index 215e1e9..2326071 100644
--- a/src/CTConfig.php
+++ b/src/CTConfig.php
@@ -159,7 +159,7 @@ public static function getSessionCookie(): ?array
         if (empty($cookieData)) {
             return null;
         }
-        return end($cookieData);
+        return array_pop($cookieData);
     }
 
     public static function getSessionCookieString(): ?string
diff --git a/src/Models/Common/Auth/AuthRequestBuilder.php b/src/Models/Common/Auth/AuthRequestBuilder.php
index d91529e..00d02f9 100644
--- a/src/Models/Common/Auth/AuthRequestBuilder.php
+++ b/src/Models/Common/Auth/AuthRequestBuilder.php
@@ -7,6 +7,7 @@
 use CTApi\Exceptions\CTRequestException;
 use CTApi\Models\Groups\Person\Person;
 use CTApi\Utils\CTResponseUtil;
+use GuzzleHttp\Cookie\SetCookie;
 
 class AuthRequestBuilder
 {
@@ -74,12 +75,13 @@ public function authWithLoginToken(string $loginToken): Auth
     public function authWithSessionCookie(string $cookieString): Auth
     {
         $client = CTClient::getClient();
+        $cookie = SetCookie::fromString($cookieString);
 
         try {
             $response = $client->get('/api/whoami', [
                 'headers' => [
-                    'cookie' => $cookieString,
-                ]
+                    'cookie' => $cookie->getName() . '=' . $cookie->getValue(),
+                ],
             ]);
             $data = CTResponseUtil::dataAsArray($response);
             $person = Person::createModelFromData($data);