diff --git a/lib/Froxlor/Install/Install/Core.php b/lib/Froxlor/Install/Install/Core.php
index 234f4ae2..3ba10023 100644
--- a/lib/Froxlor/Install/Install/Core.php
+++ b/lib/Froxlor/Install/Install/Core.php
@@ -420,7 +420,7 @@ class Core
 		}
 
 		$this->updateSetting($upd_stmt, $this->validatedData['activate_newsfeed'], 'admin', 'show_news_feed');
-		$this->updateSetting($upd_stmt, dirname(__FILE__, 3), 'system', 'letsencryptchallengepath');
+		$this->updateSetting($upd_stmt, dirname(__FILE__, 5), 'system', 'letsencryptchallengepath');
 
 		// insert the lastcronrun to be the installation date
 		$this->updateSetting($upd_stmt, time(), 'system', 'lastcronrun');
diff --git a/lib/Froxlor/PhpHelper.php b/lib/Froxlor/PhpHelper.php
index 33b1a685..5db40948 100644
--- a/lib/Froxlor/PhpHelper.php
+++ b/lib/Froxlor/PhpHelper.php
@@ -324,7 +324,7 @@ class PhpHelper
 	 * Return human-readable sizes
 	 *
 	 * @param int $size size in bytes
-	 * @param string $max maximum unit
+	 * @param ?string $max maximum unit
 	 * @param string $system 'si' for SI, 'bi' for binary prefixes
 	 * @param string $retstring string-format
 	 *
@@ -332,7 +332,7 @@ class PhpHelper
 	 */
 	public static function sizeReadable(
 		int $size,
-		string $max = '',
+		?string $max = '',
 		string $system = 'si',
 		string $retstring = '%01.2f %s'
 	): string {