diff --git a/src/ProxmoxVE.php b/src/ProxmoxVE.php
index 701593b..2fe0b92 100644
--- a/src/ProxmoxVE.php
+++ b/src/ProxmoxVE.php
@@ -154,6 +154,11 @@ public static function request(
      */
     public function __construct($credentials)
     {
+        // Check if CURL is enabled
+        if (!function_exists('curl_version')) {
+            throw new RuntimeException('PHP5-CURL needs to be enabled!');
+        }
+
         if ($credentials instanceof Credentials) {
             $this->credentials = $credentials;
 
@@ -179,7 +184,6 @@ public function __construct($credentials)
             throw new \InvalidArgumentException($errorMessage);
         }
 
-
         $this->apiUrl = $this->credentials->getApiUrl();
 
         if (!$this->authToken = $this->credentials->login()) {