diff --git a/src/Client.php b/src/Client.php
index 0678674..761ab21 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -59,6 +59,10 @@ public function push(): array
     {
         $mh = curl_multi_init();
 
+        if (!defined('CURLPIPE_MULTIPLEX')) {
+            define('CURLPIPE_MULTIPLEX', 2);
+        }
+
         curl_multi_setopt($mh, CURLMOPT_PIPELINING, CURLPIPE_MULTIPLEX);
 
         $handles = [];
diff --git a/src/Request.php b/src/Request.php
index be2cec8..63fefe4 100644
--- a/src/Request.php
+++ b/src/Request.php
@@ -63,6 +63,10 @@ public function __construct(Notification $notification, $isProductionEnv)
         $this->uri = $isProductionEnv ? $this->getProductionUrl($notification) : $this->getSandboxUrl($notification);
         $this->body = $notification->getPayload()->toJson();
 
+        if (!defined('CURL_HTTP_VERSION_2')) {
+            define('CURL_HTTP_VERSION_2', 3);
+        }
+
         $this->options = [
             CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_2,
             CURLOPT_URL => $this->uri,