diff --git a/php/src/Data/ConfigurationManager.php b/php/src/Data/ConfigurationManager.php
index 1c257946..334bb7c9 100644
--- a/php/src/Data/ConfigurationManager.php
+++ b/php/src/Data/ConfigurationManager.php
@@ -664,7 +664,7 @@ class ConfigurationManager
             // Trim all unwanted chars on both sites
             $entry = trim($entry);
             if ($entry !== "") {
-                if (!preg_match("#^/[0-1a-zA-Z/-_]+$#", $entry) && !preg_match("#^[0-1a-zA-Z_-]+$#", $entry)) {
+                if (!preg_match("#^/[.0-1a-zA-Z/-_]+$#", $entry) && !preg_match("#^[.0-1a-zA-Z_-]+$#", $entry)) {
                     throw new InvalidSettingConfigurationException("You entered unallowed characters! Problematic is " . $entry);
                 }
                 $validDirectories .= rtrim($entry, '/') . PHP_EOL;