diff --git a/src/Composer/Downloader/TransportException.php b/src/Composer/Downloader/TransportException.php
index c91897c1c..5ab5ca6f3 100644
--- a/src/Composer/Downloader/TransportException.php
+++ b/src/Composer/Downloader/TransportException.php
@@ -26,6 +26,11 @@ class TransportException extends \RuntimeException
     /** @var array<mixed> */
     protected $responseInfo = [];
 
+    public function __construct(string $message = "", int $code = 400, \Throwable $previous = null)
+    {
+        parent::__construct($message, $code, $previous);
+    }
+
     /**
      * @param array<string> $headers
      */
diff --git a/src/Composer/Installer.php b/src/Composer/Installer.php
index 5d7e7fb51..32a149856 100644
--- a/src/Composer/Installer.php
+++ b/src/Composer/Installer.php
@@ -80,6 +80,8 @@ class Installer
     // used/declared in SolverProblemsException, carried over here for completeness
     public const ERROR_DEPENDENCY_RESOLUTION_FAILED = 2;
     public const ERROR_AUDIT_FAILED = 5;
+    // technically exceptions are thrown with various status codes >400, but the process exit code is normalized to 255
+    public const ERROR_TRANSPORT_EXCEPTION = 255;
 
     /**
      * @var IOInterface