diff --git a/src/DynamoDbModel.php b/src/DynamoDbModel.php
index e37abeb..500dcb8 100644
--- a/src/DynamoDbModel.php
+++ b/src/DynamoDbModel.php
@@ -62,7 +62,7 @@ abstract class DynamoDbModel extends Model
      * Default Date format
      * ISO 8601 Compliant
      */
-    protected $dateFormat = DateTime::ISO8601;
+    protected $dateFormat = DateTime::ATOM;
 
 
     public function __construct(array $attributes = [])