diff --git a/Search/Document.php b/Search/Document.php
index 3be5f09..13da80f 100644
--- a/Search/Document.php
+++ b/Search/Document.php
@@ -245,6 +245,7 @@ public function hasField($name)
         return isset($this->fields[$name]);
     }
 
+    #[\ReturnTypeWillChange]
     public function jsonSerialize()
     {
         return [