diff --git a/.github/workflows/test-and-deploy.yml b/.github/workflows/test-and-deploy.yml
index 1f903e5..489b143 100644
--- a/.github/workflows/test-and-deploy.yml
+++ b/.github/workflows/test-and-deploy.yml
@@ -17,7 +17,7 @@ jobs:
     timeout-minutes: 20
     strategy:
       matrix:
-        php: [ '7.3', '7.4', '8.0', '8.1' ]
+        php: [ '7.3', '7.4', '8.0', '8.1', '8.2', '8.3', '8.4' ]
         dependencies:
           - "lowest"
           - "highest"
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index b183415..4218850 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -18,7 +18,7 @@ We welcome direct contributions to the php-http-client code base. Thank you!
 
 ##### Prerequisites #####
 
-- PHP version 7.3, 7.4, 8.0, or 8.1
+- PHP version 7.3+
 - [Composer](https://getcomposer.org/)
 
 ##### Initial setup: #####
diff --git a/README.md b/README.md
index 7aea5d1..1880490 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,7 @@ All updates to this library are documented in our [CHANGELOG](CHANGELOG.md).
 
 ## Prerequisites
 
-- PHP version 7.3, 7.4, 8.0, or 8.1
+- PHP version 7.3+
 
 ## Install with Composer
 
diff --git a/lib/Exception/InvalidRequest.php b/lib/Exception/InvalidRequest.php
index 21ae2ac..819172d 100644
--- a/lib/Exception/InvalidRequest.php
+++ b/lib/Exception/InvalidRequest.php
@@ -12,7 +12,7 @@ class InvalidRequest extends \Exception
     public function __construct(
         $message = '',
         $code = 0,
-        \Exception $previous = null
+        ?\Exception $previous = null
     ) {
         $message = 'Could not send request to server. ' .
             'CURL error ' . $code . ': ' . $message;