diff --git a/src/Gui/DemoMode.h b/src/Gui/DemoMode.h
index f13c7bd25e..75f7627454 100644
--- a/src/Gui/DemoMode.h
+++ b/src/Gui/DemoMode.h
@@ -23,6 +23,7 @@
 #ifndef GUI_DIALOG_DEMOMODE_H
 #define GUI_DIALOG_DEMOMODE_H
 
+#include <Inventor/SbVec3f.h>
 #include <QDialog>
 #include <FCGlobal.h>
 
@@ -45,11 +46,11 @@ class GuiExport DemoMode : public QDialog
     Q_OBJECT
 
 public:
-    DemoMode(QWidget* parent = nullptr, Qt::WindowFlags fl = Qt::WindowFlags());
-    ~DemoMode();
+    explicit DemoMode(QWidget* parent = nullptr, Qt::WindowFlags fl = Qt::WindowFlags());
+    ~DemoMode() override;
 
-    void accept();
-    void reject();
+    void accept() override;
+    void reject() override;
 
 protected:
     void setupConnections();
@@ -68,10 +69,10 @@ private:
     SbVec3f getDirection(Gui::View3DInventor*) const;
     Gui::View3DInventor* activeView() const;
     void startAnimation(Gui::View3DInventor*);
-    void changeEvent(QEvent *e);
-    bool eventFilter(QObject *, QEvent *);
-    void showEvent(QShowEvent *);
-    void hideEvent(QHideEvent *);
+    void changeEvent(QEvent *e) override;
+    bool eventFilter(QObject *, QEvent *) override;
+    void showEvent(QShowEvent *) override;
+    void hideEvent(QHideEvent *) override;
 
 private:
     int oldvalue;