diff --git a/Admin/Installer.php b/Admin/Installer.php
index d777ed5..6ad1a42 100644
--- a/Admin/Installer.php
+++ b/Admin/Installer.php
@@ -32,7 +32,7 @@ class Installer extends InstallerAbstract
     /**
      * {@inheritdoc}
      */
-    public static function install(string $path, DatabasePool $dbPool, InfoManager $info)
+    public static function install(string $path, DatabasePool $dbPool, InfoManager $info) : void
     {
         parent::install(__DIR__ . '/..', $dbPool, $info);
     }