diff --git a/composer.json b/composer.json
index 1e09dc9..1f54edd 100644
--- a/composer.json
+++ b/composer.json
@@ -28,6 +28,12 @@
     "johnpbloch/wordpress-core": ">=5.5",
     "humanmade/psalm-plugin-wordpress": "^2.0"
   },
+  "config": {
+    "allow-plugins": {
+      "dealerdirect/phpcodesniffer-composer-installer": true,
+      "composer/package-versions-deprecated": true
+    }
+  },
   "autoload": {
     "psr-4": {
       "RebelCode\\WordPress\\Http\\": "src"
diff --git a/src/WpClient.php b/src/WpClient.php
index a6253f6..bc3961d 100644
--- a/src/WpClient.php
+++ b/src/WpClient.php
@@ -27,14 +27,15 @@ class WpClient implements ClientInterface
     /**
      * Constructor.
      *
-     * @param HandlerInterface  $handler The handler to use for dispatching requests and receiving responses.
-     * @param UriInterface|null $baseUri Optional base URI for all relative requests sent using this client.
+     * @param HandlerInterface|null $handler The handler to use for dispatching requests and receiving responses.
+     *                                       Defaults to {@link HandlerStack::createDefault()} when null.
+     * @param UriInterface|null     $baseUri Optional base URI for all relative requests sent using this client.
      *
      * @throws InvalidArgumentException If the "base_uri" option is present and is not a valid URI.
      */
-    public function __construct(HandlerInterface $handler, ?UriInterface $baseUri = null)
+    public function __construct(?HandlerInterface $handler = null, ?UriInterface $baseUri = null)
     {
-        $this->handler = $handler;
+        $this->handler = $handler ?? HandlerStack::createDefault();
         $this->baseUri = $baseUri;
     }
 
diff --git a/tests/WpHandlerTest.php b/tests/WpHandlerTest.php
index 310ec31..59d9f32 100644
--- a/tests/WpHandlerTest.php
+++ b/tests/WpHandlerTest.php
@@ -11,7 +11,7 @@
 use RebelCode\Psr7\Uri;
 use RebelCode\WordPress\Http\HandlerInterface;
 use RebelCode\WordPress\Http\WpHandler;
-use Requests_Utility_CaseInsensitiveDictionary;
+use WpOrg\Requests\Utility\CaseInsensitiveDictionary;
 use WP_Error;
 use WP_Mock;
 
@@ -58,7 +58,7 @@ public function testHandle()
         {
             $statusCode = 201;
             $statusReason = 'Created';
-            $responseHeaders = new Requests_Utility_CaseInsensitiveDictionary([
+            $responseHeaders = new CaseInsensitiveDictionary([
                 'Sam' => 'Eggs, Ham',
                 'Cat' => 'Hat',
             ]);
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 3c681cf..913f750 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -7,10 +7,25 @@
 
 WP_Mock::bootstrap();
 
-if (!class_exists('Requests_Utility_CaseInsensitiveDictionary')) {
-    require WORDPRESS_DIR . '/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php';
-}
+/*
+ * Load the Requests HTTP library bundled with WordPress. WordPress 6.2 shipped Requests 2.0,
+ * which moved the library under wp-includes/Requests/src and renamed the classes from the flat
+ * Requests_* names to the WpOrg\Requests namespace. Support both layouts so the suite runs
+ * against whichever WordPress version Composer resolves across the PHP matrix.
+ */
+$newAutoload = WORDPRESS_DIR . '/wp-includes/Requests/src/Autoload.php';
+
+if (file_exists($newAutoload)) {
+    require_once $newAutoload;
+    WpOrg\Requests\Autoload::register();
+} else {
+    require_once WORDPRESS_DIR . '/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php';
 
-if (!class_exists('Requests_Exception')) {
-    require WORDPRESS_DIR . '/wp-includes/Requests/Exception.php';
+    // Pre-6.2 WordPress only defines the legacy class name; alias it to the modern one the tests use.
+    if (!class_exists(WpOrg\Requests\Utility\CaseInsensitiveDictionary::class)) {
+        class_alias(
+            'Requests_Utility_CaseInsensitiveDictionary',
+            WpOrg\Requests\Utility\CaseInsensitiveDictionary::class
+        );
+    }
 }