diff --git a/src/writers/Oaipmh.php b/src/writers/Oaipmh.php
index 9ad47d1..04cbcce 100644
--- a/src/writers/Oaipmh.php
+++ b/src/writers/Oaipmh.php
@@ -133,6 +133,8 @@ public function writeMetadataFile($metadata, $path, $overwrite = true)
     public function normalizeFilename($string)
     {
         $string = urldecode($string);
+        $pattern = '#'.DIRECTORY_SEPARATOR.'#';
+        $string = preg_replace($pattern, '-', $string);
         $string = preg_replace('/:/', '_', $string);
         return $string;
     }