diff --git a/shop/shopform.cpp b/shop/shopform.cpp
index fd3a9eb..d62030e 100644
--- a/shop/shopform.cpp
+++ b/shop/shopform.cpp
@@ -150,7 +150,7 @@ void ShopForm::on_loadButton_clicked()
     form->show();
 }
 
-void ShopForm::onCountChanged(int oldCount)
+void ShopForm::onCountChanged(int oldCount/* = 0*/)
 {
     VoucherItem *item = qobject_cast<VoucherItem*>(sender());
     if (item != NULL && item->count() == 0)
@@ -268,7 +268,7 @@ void ShopForm::addItem(QSharedPointer<IShopItem> item, int count)
     srv.addShopItem(m_voucher, item, count);
     this->m_itemsModel->addRow(m_voucher->items()[m_voucher->items().count() - 1]);
     connect(m_voucher->items()[m_voucher->items().count() - 1].data(), SIGNAL(countChanged(int)), this, SLOT(onCountChanged(int)));
-    onCountChanged(0);
+    onCountChanged();
 }
 
 void ShopForm::on_receiptCombo_currentIndexChanged(int)
diff --git a/shop/shopform.h b/shop/shopform.h
index 301823b..1542b59 100644
--- a/shop/shopform.h
+++ b/shop/shopform.h
@@ -32,7 +32,7 @@ private slots:
 
     void on_loadButton_clicked();
 
-    void onCountChanged(int oldCount);
+    void onCountChanged(int oldCount = 0);
 
     void on_receiptCombo_currentIndexChanged(int index);