diff --git a/CHANGELOG.md b/CHANGELOG.md
index 785750e..463f6d2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,10 @@
 CHANGELOG
 =========
 
+6.6.3
+-----
+* Added support for using your own GuzzleClient and HttpClient
+
 6.6.2
 -----
 * Added isDefault property to SshKey 
diff --git a/src/HttpClient/GuzzleClient.php b/src/HttpClient/GuzzleClient.php
index e9691f2..073684d 100644
--- a/src/HttpClient/GuzzleClient.php
+++ b/src/HttpClient/GuzzleClient.php
@@ -18,9 +18,9 @@ class GuzzleClient extends HttpClient
      */
     private $client;
 
-    public function __construct(string $endpoint)
+    public function __construct(string $endpoint, Client $client = null)
     {
-        $this->client = new Client();
+        $this->client = $client ?? new Client();
         parent::__construct($endpoint);
     }
 
diff --git a/src/TransipAPI.php b/src/TransipAPI.php
index 5bf0089..aca8e9c 100644
--- a/src/TransipAPI.php
+++ b/src/TransipAPI.php
@@ -58,7 +58,7 @@
 class TransipAPI
 {
     public const TRANSIP_API_ENDPOINT = "https://api.transip.nl/v6";
-    public const TRANSIP_API_LIBRARY_VERSION = "6.6.2";
+    public const TRANSIP_API_LIBRARY_VERSION = "6.6.3";
     public const TRANSIP_API_DEMO_TOKEN = "eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiIsImp0aSI6ImN3MiFSbDU2eDNoUnkjelM4YmdOIn0.eyJpc3MiOiJhcGkudHJhbnNpcC5ubCIsImF1ZCI6ImFwaS50cmFuc2lwLm5sIiwianRpIjoiY3cyIVJsNTZ4M2hSeSN6UzhiZ04iLCJpYXQiOjE1ODIyMDE1NTAsIm5iZiI6MTU4MjIwMTU1MCwiZXhwIjoyMTE4NzQ1NTUwLCJjaWQiOiI2MDQ0OSIsInJvIjpmYWxzZSwiZ2siOmZhbHNlLCJrdiI6dHJ1ZX0.fYBWV4O5WPXxGuWG-vcrFWqmRHBm9yp0PHiYh_oAWxWxCaZX2Rf6WJfc13AxEeZ67-lY0TA2kSaOCp0PggBb_MGj73t4cH8gdwDJzANVxkiPL1Saqiw2NgZ3IHASJnisUWNnZp8HnrhLLe5ficvb1D9WOUOItmFC2ZgfGObNhlL2y-AMNLT4X7oNgrNTGm-mespo0jD_qH9dK5_evSzS3K8o03gu6p19jxfsnIh8TIVRvNdluYC2wo4qDl5EW5BEZ8OSuJ121ncOT1oRpzXB0cVZ9e5_UVAEr9X3f26_Eomg52-PjrgcRJ_jPIUYbrlo06KjjX2h0fzMr21ZE023Gw";
 
     /**
@@ -80,7 +80,8 @@ public function __construct(
         bool $generateWhitelistOnlyTokens = true,
         string $token = '',
         string $endpointUrl = '',
-        AdapterInterface $cache = null
+        AdapterInterface $cache = null,
+        GuzzleClient $httpClient = null
     ) {
         $endpoint = self::TRANSIP_API_ENDPOINT;
 
@@ -88,7 +89,7 @@ public function __construct(
             $endpoint = $endpointUrl;
         }
 
-        $this->httpClient = new GuzzleClient($endpoint);
+        $this->httpClient = $httpClient ?? new GuzzleClient($endpoint);
 
         if ($customerLoginName != '') {
             $this->httpClient->setLogin($customerLoginName);