diff --git a/src/Guzzle/Http/Message/Response.php b/src/Guzzle/Http/Message/Response.php
index fada796b..258ffdc6 100644
--- a/src/Guzzle/Http/Message/Response.php
+++ b/src/Guzzle/Http/Message/Response.php
@@ -49,6 +49,7 @@ class Response extends AbstractMessage
         415 => 'Unsupported Media Type',
         416 => 'Requested Range Not Satisfiable',
         417 => 'Expectation Failed',
+        422 => 'Unprocessable Entity',
         500 => 'Internal Server Error',
         501 => 'Not Implemented',
         502 => 'Bad Gateway',