diff --git a/product/ERP5/Document/File.py b/product/ERP5/Document/File.py
index 68db9fc3204e9aa05f7ae683f8f78a84b64d1a52..87d6992e5a17e24d5fc2fb20e49ba19a8a251d96 100644
--- a/product/ERP5/Document/File.py
+++ b/product/ERP5/Document/File.py
@@ -225,8 +225,7 @@ class File(Document, CMFFile):
 
     return (mime_type, content)
 
-  security.declareProtected(Permissions.AccessContentsInformation, 'convert')
-  def convert(self, format, **kw):
+  def _convert(self, format, **kw):
     """According content_type of data we can proceed some Conversions.
     The idea is to wrap data into TempDocument who support conversion
     then return conversion from this temporary document.