diff --git a/misc-scripts/surgery/SeqStoreConverter/BasicConverter.pm b/misc-scripts/surgery/SeqStoreConverter/BasicConverter.pm
index 20a0375bf114bcc4d318e00aa2ddee56683cbf5b..20c128855c7c8ff92c2bc30035776d999827fa61 100644
--- a/misc-scripts/surgery/SeqStoreConverter/BasicConverter.pm
+++ b/misc-scripts/surgery/SeqStoreConverter/BasicConverter.pm
@@ -284,7 +284,7 @@ sub clone_to_seq_region {
   my $select_sth = $dbh->prepare
     ("SELECT cl.clone_id,
              CONCAT(cl.embl_acc, '.', cl.embl_version),
-             MAX(ctg.embl_offset)+ctg.length-1
+             MAX(ctg.embl_offset+ctg.length-1)
      FROM   $source.clone cl, $source.contig ctg
 		 WHERE  cl.clone_id = ctg.clone_id GROUP BY ctg.clone_id");
   $select_sth->execute();
diff --git a/misc-scripts/surgery/SeqStoreConverter/MusMusculus.pm b/misc-scripts/surgery/SeqStoreConverter/MusMusculus.pm
index 2c7782754660bb0b6cf65aaaefbb6d1407ad924b..c826c4f07cda5f7a3fc64b05c96cfae39aa74b77 100644
--- a/misc-scripts/surgery/SeqStoreConverter/MusMusculus.pm
+++ b/misc-scripts/surgery/SeqStoreConverter/MusMusculus.pm
@@ -179,7 +179,7 @@ sub clone_to_seq_region {
   my $select_sth = $dbh->prepare
     ("SELECT cl.clone_id,
              CONCAT(cl.embl_acc, '.', cl.embl_version),
-             MAX(ctg.embl_offset)+ctg.length-1
+             MAX(ctg.embl_offset+ctg.length-1)
      FROM   $source.clone cl, $source.contig ctg
 		 WHERE  cl.clone_id = ctg.clone_id
      AND    cl.embl_acc not like 'C%'