diff --git a/source/java/org/alfresco/repo/transfer/ContentDataPart.java b/source/java/org/alfresco/repo/transfer/ContentDataPart.java
index 6d6b36228b..343bc5c8e6 100644
--- a/source/java/org/alfresco/repo/transfer/ContentDataPart.java
+++ b/source/java/org/alfresco/repo/transfer/ContentDataPart.java
@@ -81,7 +81,7 @@ public class ContentDataPart extends PartBase
     @Override
     protected long lengthOfData() throws IOException
     {
-        return data.getSize();
+        return contentService.getRawReader(data.getContentUrl()).getSize();
     }
 
     /* (non-Javadoc)