diff --git a/installer/data/mysql/atomicupdate/bug_20773.perl b/installer/data/mysql/atomicupdate/bug_20773.perl
new file mode 100644
index 0000000000..d93d30433f
--- /dev/null
+++ b/installer/data/mysql/atomicupdate/bug_20773.perl
@@ -0,0 +1,11 @@
+$DBversion = 'XXX';  # will be replaced by the RM
+if( CheckVersion( $DBversion ) ) {
+    my $dtf   = Koha::Database->new->schema->storage->datetime_parser;
+    my $days = C4::Context->preference('MaxPickupDelay') || 7;
+    my $date = DateTime->now()->add( days => $days );
+    my $sql = q|UPDATE reserves SET expirationdate = ? WHERE expirationdate IS NULL AND waitingdate IS NOT NULL|;
+    $dbh->do( $sql, undef, $dtf->format_datetime($date) );
+
+    SetVersion( $DBversion );
+    print "Upgrade to $DBversion done (Bug 20724 - expirationdate filled for waiting holds)\n";
+}