diff --git a/src/Exception/JobRuntimeException.php b/src/Exception/JobRuntimeException.php
index 7c025b3..ecf213e 100644
--- a/src/Exception/JobRuntimeException.php
+++ b/src/Exception/JobRuntimeException.php
@@ -15,7 +15,7 @@ public function __construct(
         protected JobInterface $job,
         string $message,
         int $code = 0,
-        \Throwable $previous = null,
+        ?\Throwable $previous = null,
     ) {
         parent::__construct($message, $code, $previous);
     }