diff --git a/src/omero_mkngff/__init__.py b/src/omero_mkngff/__init__.py
index 0bb76a9..5697c0f 100644
--- a/src/omero_mkngff/__init__.py
+++ b/src/omero_mkngff/__init__.py
@@ -104,8 +104,7 @@
           values (nextval('seq_filesetentry'), {DETAILS2},
                   new_fileset, new_file, i-1, 'unknown');
 
-      -- use the third file as the target for setId (assumed to be the first .zattrs)
-      if i = 3 then
+      if info[i][2] = 'METADATA.ome.xml' then
           update pixels set path = trim(trailing '/' from info[i][1]), name = info[i][2]
             from (select id from image where image.fileset = old_fileset) as subquery
            where pixels.image = subquery.id;