diff --git a/samples/blackgui/mainwindow.cpp b/samples/blackgui/mainwindow.cpp
index a8a44b979..349c0da56 100644
--- a/samples/blackgui/mainwindow.cpp
+++ b/samples/blackgui/mainwindow.cpp
@@ -391,7 +391,9 @@ void MainWindow::changeWindowOpacity(int opacity)
             return;
     }
     qreal o = opacity / 100.0;
+    o = o < 0.3 ? 0.3 : o;
     QWidget::setWindowOpacity(o);
+    this->ui->hs_SettingsGuiOpacity->setValue(o * 100.0);
 }
 
 /*
diff --git a/samples/blackgui/mainwindow_init.cpp b/samples/blackgui/mainwindow_init.cpp
index 119695f50..0878f8ad8 100644
--- a/samples/blackgui/mainwindow_init.cpp
+++ b/samples/blackgui/mainwindow_init.cpp
@@ -184,8 +184,10 @@ void MainWindow::initGuiSignals()
     Q_ASSERT(connected);
     connected = this->connect(this->ui->pb_MainWeather, SIGNAL(released()), this, SLOT(setMainPage()));
     Q_ASSERT(connected);
-    this->connect(this->ui->pb_MainKeypadOpacity050, &QPushButton::clicked, this, &MainWindow::changeWindowOpacity);
-    this->connect(this->ui->pb_MainKeypadOpacity100, &QPushButton::clicked, this, &MainWindow::changeWindowOpacity);
+    connected = this->connect(this->ui->pb_MainKeypadOpacity050, SIGNAL(clicked()), this, SLOT(changeWindowOpacity()));
+    Q_ASSERT(connected);
+    connected = this->connect(this->ui->pb_MainKeypadOpacity100, SIGNAL(clicked()), this, SLOT(changeWindowOpacity()));
+    Q_ASSERT(connected);
 
     // Sound buttons
     this->connect(this->ui->pb_SoundMute, &QPushButton::clicked, this, &MainWindow::audioVolumes);