use SL::DB::MetaSetup::PurchaseInvoice;
 use SL::DB::Manager::PurchaseInvoice;
+use SL::DB::Helper::LinkedRecords;
+# The calculator hasn't been adjusted for purchase invoices yet.
+# use SL::DB::Helper::PriceTaxCalculator;
 
 __PACKAGE__->meta->add_relationship(invoiceitems => { type         => 'one to many',
                                                       class        => 'SL::DB::InvoiceItem',