diff --git a/launcher/firstLaunch/firstlaunch_moc.cpp b/launcher/firstLaunch/firstlaunch_moc.cpp
index d7992c656..0fb7abe0c 100644
--- a/launcher/firstLaunch/firstlaunch_moc.cpp
+++ b/launcher/firstLaunch/firstlaunch_moc.cpp
@@ -318,9 +318,8 @@ QString FirstLaunchView::getHeroesInstallDir()
 void FirstLaunchView::extractGogData()
 {
 #ifdef ENABLE_INNOEXTRACT
-	auto fileSelection = [this](QByteArray magic, QString filter, QString startPath = {}) {
+	auto fileSelection = [this](QString filter, QString startPath = {}) {
 		QString titleSel = tr("Select %1 file...", "param is file extension").arg(filter);
-		QString titleErr = tr("You have to select %1 file!", "param is file extension").arg(filter);
 #if defined(VCMI_MOBILE)
 		filter = tr("GOG file (*.*)");
 		QMessageBox::information(this, tr("File selection"), titleSel);
@@ -328,27 +327,35 @@ void FirstLaunchView::extractGogData()
 		QString file = QFileDialog::getOpenFileName(this, titleSel, startPath.isEmpty() ? QDir::homePath() : startPath, filter);
 		if(file.isEmpty())
 			return QString{};
-		
-		QFile tmpFile(file);
+		return file;
+	};
+
+	auto checkMagic = [this](QString filename, QString filter, QByteArray magic)
+	{
+		QString titleErr = tr("You have to select %1 file!", "param is file extension").arg(filter);
+
+		QFile tmpFile(filename);
 		if(!tmpFile.open(QIODevice::ReadOnly))
 		{
 			QMessageBox::critical(this, tr("File cannot be opened"), tmpFile.errorString());
-			return QString{};
+			return false;
 		}
 		QByteArray magicFile = tmpFile.read(magic.length());
 		if(!magicFile.startsWith(magic))
 		{
 			QMessageBox::critical(this, tr("Invalid file selected"), titleErr);
-			return QString{};
+			return false;
 		}
-
-		return file;
+		return true;
 	};
 
-	QString fileBin = fileSelection(QByteArray{"idska32"}, tr("GOG data") + " (*.bin)");
+	QString filterBin = tr("GOG data") + " (*.bin)";
+	QString filterExe = tr("GOG installer") + " (*.exe)";
+
+	QString fileBin = fileSelection(filterBin);
 	if(fileBin.isEmpty())
 		return;
-	QString fileExe = fileSelection(QByteArray{"MZ"}, tr("GOG installer") + " (*.exe)", QFileInfo(fileBin).absolutePath());
+	QString fileExe = fileSelection(filterExe, QFileInfo(fileBin).absolutePath());
 	if(fileExe.isEmpty())
 		return;
 
@@ -356,7 +363,7 @@ void FirstLaunchView::extractGogData()
 	ui->pushButtonGogInstall->setVisible(false);
 	setEnabled(false);
 
-	QTimer::singleShot(100, this, [this, fileExe, fileBin](){ // background to make sure FileDialog is closed...
+	QTimer::singleShot(100, this, [this, fileExe, fileBin, checkMagic, filterBin, filterExe](){ // background to make sure FileDialog is closed...
 		QDir tempDir(pathToQString(VCMIDirs::get().userDataPath()));
 		if(tempDir.cd("tmp"))
 		{
@@ -373,6 +380,10 @@ void FirstLaunchView::extractGogData()
 		Helper::performNativeCopy(fileExe, tmpFileExe);
 		Helper::performNativeCopy(fileBin, tmpFileBin);
 
+		if (!checkMagic(tmpFileBin, filterBin, QByteArray{"idska32"}) ||
+		   !checkMagic(tmpFileExe, filterExe, QByteArray{"MZ"}))
+			return;
+
 		logGlobal->info("Installing exe '%s' ('%s')", tmpFileExe.toStdString(), fileExe.toStdString());
 		logGlobal->info("Installing bin '%s' ('%s')", tmpFileBin.toStdString(), fileBin.toStdString());