diff --git a/ext_localconf.php b/ext_localconf.php
index c8bbee3..daf382c 100644
--- a/ext_localconf.php
+++ b/ext_localconf.php
@@ -2,7 +2,7 @@
 
 defined('TYPO3_MODE') or die('Access denied.');
 
-(static function () {
+(static function (): void {
     // This makes the plugin available for front-end rendering.
     \TYPO3\CMS\Extbase\Utility\ExtensionUtility::configurePlugin(
         // extension name, matching the PHP namespaces (but without the vendor)