diff --git a/README.md b/README.md
index c3f1406..522cbaf 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # Pushok
 
-[![PHP >= 7.2](https://img.shields.io/badge/php-%3E%3D%208.0-8892BF.svg?style=flat-square)](https://php.net/)
+[![PHP >= 8.0](https://img.shields.io/badge/php-%3E%3D%208.0-8892BF.svg?style=flat-square)](https://php.net/)
 [![Build Status][ico-travis]][link-travis]
 [![Latest Version on Packagist][ico-version]][link-packagist]
 [![Total Downloads][ico-downloads]][link-downloads]
diff --git a/src/Payload.php b/src/Payload.php
index 5932234..b75b694 100644
--- a/src/Payload.php
+++ b/src/Payload.php
@@ -458,6 +458,7 @@ public function toJson(): string
      * @return array
      * @link   http://php.net/manual/en/jsonserializable.jsonserialize.php
      */
+    #[\ReturnTypeWillChange]
     public function jsonSerialize()
     {
         $payload = self::getDefaultPayloadStructure();
diff --git a/src/Payload/Alert.php b/src/Payload/Alert.php
index 46c0959..bb4f1e7 100644
--- a/src/Payload/Alert.php
+++ b/src/Payload/Alert.php
@@ -325,6 +325,7 @@ public function toJson(): string
      * @return array
      * @link   http://php.net/manual/en/jsonserializable.jsonserialize.php
      */
+    #[\ReturnTypeWillChange]
     public function jsonSerialize()
     {
         $alert = [];
diff --git a/src/Payload/Sound.php b/src/Payload/Sound.php
index 03053bd..2ac1ea8 100644
--- a/src/Payload/Sound.php
+++ b/src/Payload/Sound.php
@@ -139,6 +139,7 @@ public function toJson(): string
      * @return array
      * @link   http://php.net/manual/en/jsonserializable.jsonserialize.php
      */
+    #[\ReturnTypeWillChange]
     public function jsonSerialize()
     {
         $sound = [];