diff --git a/src/Client/Payload.php b/src/Client/Payload.php
index 0ab06a8..4b6eadd 100644
--- a/src/Client/Payload.php
+++ b/src/Client/Payload.php
@@ -33,7 +33,7 @@ class Payload implements \ArrayAccess, \JsonSerializable
 		$data = json_decode((string)$json,true);
 
 		if (json_last_error() !== JSON_ERROR_NONE || (! is_array($data))) {
-			throw new \UnexpectedValueException('Invalid JSON message.');
+			throw new \UnexpectedValueException('Invalid JSON message:'.serialize($data));
 		}
 
 		return new static($data);