diff --git a/gui/gui.pro b/gui/gui.pro
index 9b9c73af9..2ac6ec09a 100644
--- a/gui/gui.pro
+++ b/gui/gui.pro
@@ -4,7 +4,7 @@ greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
 TARGET = gui
 TEMPLATE = app
 
-SOURCES += ../bip32.c ../bip39.c ../sha2.c ../pbkdf2.c ../hmac.c ../rand.c ../bignum.c ../ecdsa.c ../ripemd160.c ../base58.c ../secp256k1.c mainwindow.cpp main.cpp
+SOURCES += ../bip32.c ../bip39.c ../sha2.c ../pbkdf2.c ../hmac.c ../rand.c ../bignum.c ../ecdsa.c ../ripemd160.c ../base58.c ../secp256k1.c ../nist256p1.c mainwindow.cpp main.cpp
 
 HEADERS += mainwindow.h ../bip32.h ../bip39.h
 
diff --git a/gui/mainwindow.cpp b/gui/mainwindow.cpp
index b3a19296f..a67d28857 100644
--- a/gui/mainwindow.cpp
+++ b/gui/mainwindow.cpp
@@ -45,7 +45,8 @@ void MainWindow::on_spinAccount_valueChanged(int arg1)
 {
     if (!root_set) return;
     const char addr_version = 0x00, wif_version = 0x80;
-    char buf[128];
+    const size_t buflen = 128;
+    char buf[buflen + 1];
     HDNode node;
     // external chain
     for (int chain = 0; chain < 2; chain++) {
@@ -54,14 +55,14 @@ void MainWindow::on_spinAccount_valueChanged(int arg1)
         hdnode_private_ckd(&node, 44 | 0x80000000);
         hdnode_private_ckd(&node, 0 | 0x80000000); // bitcoin
         hdnode_private_ckd(&node, (arg1 - 1) | 0x80000000);
-        hdnode_serialize_private(&node, buf); QString xprv = QString(buf); ui->lineXprv->setText(xprv);
-        hdnode_serialize_public(&node, buf); QString xpub = QString(buf); ui->lineXpub->setText(xpub);
+        hdnode_serialize_private(&node, buf, buflen); QString xprv = QString(buf); ui->lineXprv->setText(xprv);
+        hdnode_serialize_public(&node, buf, buflen); QString xpub = QString(buf); ui->lineXpub->setText(xpub);
         hdnode_private_ckd(&node, chain); // external / internal
         for (int i = 0; i < 100; i++) {
             HDNode node2 = node;
             hdnode_private_ckd(&node2, i);
-            ecdsa_get_address(node2.public_key, addr_version, buf); QString address = QString(buf);
-            ecdsa_get_wif(node2.private_key, wif_version, buf); QString wif = QString(buf);
+            ecdsa_get_address(node2.public_key, addr_version, buf, buflen); QString address = QString(buf);
+            ecdsa_get_wif(node2.private_key, wif_version, buf, buflen); QString wif = QString(buf);
             list->setItem(i, 0, new QTableWidgetItem(address));
             list->setItem(i, 1, new QTableWidgetItem(wif));
             list->setItem(i, 2, new QTableWidgetItem("0.0"));