diff --git a/webdav-derivative-test.php b/webdav-derivative-test.php
index 2ef4b0a..ea9cf1f 100644
--- a/webdav-derivative-test.php
+++ b/webdav-derivative-test.php
@@ -54,7 +54,7 @@ function bratonien_tools_webdav_derivative_test_source_info($image_id, array $im
   $resolved = realpath($absolute);
   if ($resolved === false) return null;
 
-  $normalized = str_replace('\\\\', '/', $resolved);
+  $normalized = str_replace('\\', '/', $resolved);
   if (!preg_match('#/nc-webdav-source/connection-([0-9]+)/root-([0-9]+)/(.*)$#', $normalized, $match))
   {
     return null;
@@ -300,7 +300,8 @@ if (!$source)
   bratonien_tools_webdav_derivative_test_abort(404, 'Keine WebDAV-Quelle fuer dieses Bild gefunden.');
 }
 
-$test_rel_dir = trim(PWG_DERIVATIVE_DIR, '/').'/bratonien-webdav-test';
+$upload_dir = rtrim((string)($GLOBALS['conf']['upload_dir'] ?? './upload'), '/');
+$test_rel_dir = $upload_dir.'/bratonien-webdav-test';
 $test_root = PHPWG_ROOT_PATH.$test_rel_dir;
 if (!is_dir($test_root) && !@mkdir($test_root, 0755, true))
 {
@@ -328,7 +329,7 @@ if (!in_array($extension, array('jpg', 'jpeg', 'png', 'gif', 'webp'), true))
 $token = getmypid().'-'.bin2hex(random_bytes(6));
 $source_filename = 'source-'.$image_id.'-'.$token.'.'.$extension;
 $source_path = $test_root.'/'.$source_filename;
-$source_rel = './'.$test_rel_dir.'/'.$source_filename;
+$source_rel = $test_rel_dir.'/'.$source_filename;
 $temp_image_id = 0;
 $derivative_path = '';
 $cleaned = false;