diff --git a/installer/data/mysql/atomicupdate/bug_35610.pl b/installer/data/mysql/atomicupdate/bug_35610.pl
index e9e2c10725..6143bd9e11 100755
--- a/installer/data/mysql/atomicupdate/bug_35610.pl
+++ b/installer/data/mysql/atomicupdate/bug_35610.pl
@@ -8,6 +8,12 @@ return {
         my ( $dbh, $out ) = @$args{qw(dbh out)};
 
         unless ( foreign_key_exists('old_reserves', 'old_reserves_ibfk_branchcode') ) {
+            $dbh->do(q{
+                UPDATE old_reserves
+                SET branchcode = NULL
+                WHERE branchcode NOT IN (SELECT branchcode FROM branches)
+            });
+
             $dbh->do(q{
                 ALTER TABLE old_reserves
                 ADD CONSTRAINT `old_reserves_ibfk_branchcode` FOREIGN KEY (`branchcode`) REFERENCES `branches` (`branchcode`) ON DELETE SET NULL ON UPDATE CASCADE;