diff --git a/classes/Tools.php b/classes/Tools.php
index 80151c27e..d45f7f973 100644
--- a/classes/Tools.php
+++ b/classes/Tools.php
@@ -2188,7 +2188,7 @@ FileETag INode MTime Size
 
 		foreach ($files as $file)
 			if (strpos($file, $real_ext) && strpos($file, $real_ext) == (strlen($file) - $real_ext_length))
-				$filtered_files[] = $dir.'/'.$file;
+				$filtered_files[] = $dir.DIRECTORY_SEPARATOR.$file;
 		return $filtered_files;
 	}