diff --git a/pds4_utils/write.py b/pds4_utils/write.py
index 23f21b3..d78cc4b 100755
--- a/pds4_utils/write.py
+++ b/pds4_utils/write.py
@@ -86,6 +86,7 @@ def set_if_exists(root, xpath, value):
 
     # write the filename, checksum and number of records into the template
     set_if_exists(root, '/pds:Product_Collection/pds:File_Area_Inventory/pds:Inventory/pds:records', len(index))
+    set_if_exists(root, '/pds:Product_Collection/pds:File_Area_Inventory/pds:Inventory/pds:object_length', os.path.getsize(csv_file))
     set_if_exists(root, '/pds:Product_Collection/pds:File_Area_Inventory/pds:File/pds:records', len(index))
     set_if_exists(root, '/pds:Product_Collection/pds:File_Area_Inventory/pds:File/pds:file_name', collection_csv)
     set_if_exists(root, '/pds:Product_Collection/pds:File_Area_Inventory/pds:File/pds:md5_checksum', common.md5_hash(csv_file))