diff --git a/openerp/addons/base/ir/ir_attachment.py b/openerp/addons/base/ir/ir_attachment.py
index 1cd9ed94d4c..3bf0dc3ae24 100644
--- a/openerp/addons/base/ir/ir_attachment.py
+++ b/openerp/addons/base/ir/ir_attachment.py
@@ -83,7 +83,7 @@ class ir_attachment(osv.osv):
             if bin_size:
                 r = os.path.getsize(full_path)
             else:
-                r = open(full_path).read().encode('base64')
+                r = open(full_path,'rb').read().encode('base64')
         except IOError:
             _logger.error("_read_file reading %s",full_path)
         return r