diff --git a/src/MD_STD.php b/src/MD_STD.php
index c6fc24a..262ad61 100644
--- a/src/MD_STD.php
+++ b/src/MD_STD.php
@@ -594,7 +594,7 @@ final class MD_STD {
         \curl_close($ch);
 
         $mime_type = MD_STD::mime_content_type($tmp_file);
-        \unlink($tmp_file);
+        self::unlink($tmp_file);
 
         return $mime_type;