diff --git a/product/ERP5/Tool/ContributionTool.py b/product/ERP5/Tool/ContributionTool.py
index e31c905c25ce2b874c7a19599e6c316b46c91ef6..d703e3e9439042cd2db1137fd66dba73dd3d0d5a 100644
--- a/product/ERP5/Tool/ContributionTool.py
+++ b/product/ERP5/Tool/ContributionTool.py
@@ -203,14 +203,8 @@ class ContributionTool(BaseTool):
 
     if portal_type is None:
       # Guess it with help of portal_contribution_registry
-
-      # XXX may be broken for non-cStringIO files / IO that cant be replayed?
-      data = file_object.read()
-      file_object.seek(0)
-
       registry = portal.portal_contribution_registry
       portal_type = registry.findPortalTypeName(filename=filename,
-                                                data=data,
                                                 content_type=content_type)
     #
     # Check if same file is already exists. if it exists, then update it.