diff --git a/.gitignore b/.gitignore
index 6df236f2..f4581bc8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,4 @@
-.php_cs.cache
+.php-cs-fixer.cache
 .phpunit.result.cache
 composer.lock
 composer.phar
diff --git a/.php_cs b/.php-cs-fixer.php
similarity index 84%
rename from .php_cs
rename to .php-cs-fixer.php
index 8527a007..0662d9e6 100644
--- a/.php_cs
+++ b/.php-cs-fixer.php
@@ -7,8 +7,8 @@
     ])
 ;
 
-return PhpCsFixer\Config::create()
-    ->setRules([
+$config = new PhpCsFixer\Config();
+return $config->setRules([
         '@Symfony' => true,
 
         'array_syntax' => ['syntax' => 'short'],
diff --git a/composer.json b/composer.json
index 684cd01a..fab8e39a 100644
--- a/composer.json
+++ b/composer.json
@@ -24,7 +24,7 @@
         "psr/http-factory": "^1.0"
     },
     "require-dev": {
-        "friendsofphp/php-cs-fixer": "^2.0",
+        "friendsofphp/php-cs-fixer": "^3.0",
         "phpunit/phpunit": "^9.5",
         "guzzlehttp/psr7": "^2.0",
         "php-mock/php-mock-phpunit": "^2.6"
diff --git a/src/Redmine/Api/Issue.php b/src/Redmine/Api/Issue.php
index 10a8b68d..78418786 100644
--- a/src/Redmine/Api/Issue.php
+++ b/src/Redmine/Api/Issue.php
@@ -11,11 +11,11 @@
  */
 class Issue extends AbstractApi
 {
-    const PRIO_LOW = 1;
-    const PRIO_NORMAL = 2;
-    const PRIO_HIGH = 3;
-    const PRIO_URGENT = 4;
-    const PRIO_IMMEDIATE = 5;
+    public const PRIO_LOW = 1;
+    public const PRIO_NORMAL = 2;
+    public const PRIO_HIGH = 3;
+    public const PRIO_URGENT = 4;
+    public const PRIO_IMMEDIATE = 5;
 
     /**
      * List issues.
diff --git a/tests/Unit/Client/NativeCurlClientTest.php b/tests/Unit/Client/NativeCurlClientTest.php
index 904fd61c..612f2235 100644
--- a/tests/Unit/Client/NativeCurlClientTest.php
+++ b/tests/Unit/Client/NativeCurlClientTest.php
@@ -16,9 +16,9 @@ class NativeCurlClientTest extends TestCase
 {
     use PHPMock;
 
-    const __NAMESPACE__ = 'Redmine\Client';
+    public const __NAMESPACE__ = 'Redmine\Client';
 
-    const DEFAULT_CURL_OPTIONS = [
+    public const DEFAULT_CURL_OPTIONS = [
         CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
         CURLOPT_PORT => 80,
         CURLOPT_URL => 'http://test.local/path',