diff --git a/tabbox/clientmodel.h b/tabbox/clientmodel.h
--- a/tabbox/clientmodel.h
+++ b/tabbox/clientmodel.h
@@ -58,12 +58,12 @@
         CloseableRole = Qt::UserRole + 7 ///< TabBoxClient can be closed
     };
     explicit ClientModel(QObject* parent = nullptr);
-    ~ClientModel();
-    virtual QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const;
-    virtual int columnCount(const QModelIndex& parent = QModelIndex()) const;
-    virtual int rowCount(const QModelIndex& parent = QModelIndex()) const;
-    virtual QModelIndex parent(const QModelIndex& child) const;
-    virtual QModelIndex index(int row, int column, const QModelIndex& parent = QModelIndex()) const;
+    ~ClientModel() override;
+    QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const override;
+    int columnCount(const QModelIndex& parent = QModelIndex()) const override;
+    int rowCount(const QModelIndex& parent = QModelIndex()) const override;
+    QModelIndex parent(const QModelIndex& child) const override;
+    QModelIndex index(int row, int column, const QModelIndex& parent = QModelIndex()) const override;
     Q_INVOKABLE QString longestCaption() const;
 
     /**
diff --git a/tabbox/desktopmodel.h b/tabbox/desktopmodel.h
--- a/tabbox/desktopmodel.h
+++ b/tabbox/desktopmodel.h
@@ -52,13 +52,13 @@
         ClientModelRole = Qt::UserRole + 2 ///< Clients on this desktop
     };
     explicit DesktopModel(QObject* parent = nullptr);
-    ~DesktopModel();
+    ~DesktopModel() override;
 
-    virtual QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const;
-    virtual int columnCount(const QModelIndex& parent = QModelIndex()) const;
-    virtual int rowCount(const QModelIndex& parent = QModelIndex()) const;
-    virtual QModelIndex parent(const QModelIndex& child) const;
-    virtual QModelIndex index(int row, int column, const QModelIndex& parent = QModelIndex()) const;
+    QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const override;
+    int columnCount(const QModelIndex& parent = QModelIndex()) const override;
+    int rowCount(const QModelIndex& parent = QModelIndex()) const override;
+    QModelIndex parent(const QModelIndex& child) const override;
+    QModelIndex index(int row, int column, const QModelIndex& parent = QModelIndex()) const override;
     Q_INVOKABLE QString longestCaption() const;
 
     /**
diff --git a/tabbox/tabbox.h b/tabbox/tabbox.h
--- a/tabbox/tabbox.h
+++ b/tabbox/tabbox.h
@@ -51,27 +51,27 @@
 {
 public:
     explicit TabBoxHandlerImpl(TabBox* tabBox);
-    virtual ~TabBoxHandlerImpl();
-
-    virtual int activeScreen() const;
-    virtual QWeakPointer< TabBoxClient > activeClient() const;
-    virtual int currentDesktop() const;
-    virtual QString desktopName(TabBoxClient* client) const;
-    virtual QString desktopName(int desktop) const;
-    virtual bool isKWinCompositing() const;
-    virtual QWeakPointer< TabBoxClient > nextClientFocusChain(TabBoxClient* client) const;
-    virtual QWeakPointer< TabBoxClient > firstClientFocusChain() const;
-    virtual bool isInFocusChain (TabBoxClient* client) const;
-    virtual int nextDesktopFocusChain(int desktop) const;
-    virtual int numberOfDesktops() const;
-    virtual TabBoxClientList stackingOrder() const;
-    virtual void elevateClient(TabBoxClient* c, QWindow *tabbox, bool elevate) const;
-    virtual void raiseClient(TabBoxClient *client) const;
-    virtual void restack(TabBoxClient *c, TabBoxClient *under);
-    virtual void shadeClient(TabBoxClient *c, bool b) const;
-    virtual QWeakPointer< TabBoxClient > clientToAddToList(KWin::TabBox::TabBoxClient* client, int desktop) const;
-    virtual QWeakPointer< TabBoxClient > desktopClient() const;
-    virtual void activateAndClose();
+    ~TabBoxHandlerImpl() override;
+
+    int activeScreen() const override;
+    QWeakPointer< TabBoxClient > activeClient() const override;
+    int currentDesktop() const override;
+    QString desktopName(TabBoxClient* client) const override;
+    QString desktopName(int desktop) const override;
+    bool isKWinCompositing() const override;
+    QWeakPointer< TabBoxClient > nextClientFocusChain(TabBoxClient* client) const override;
+    QWeakPointer< TabBoxClient > firstClientFocusChain() const override;
+    bool isInFocusChain (TabBoxClient* client) const override;
+    int nextDesktopFocusChain(int desktop) const override;
+    int numberOfDesktops() const override;
+    TabBoxClientList stackingOrder() const override;
+    void elevateClient(TabBoxClient* c, QWindow *tabbox, bool elevate) const override;
+    void raiseClient(TabBoxClient *client) const override;
+    void restack(TabBoxClient *c, TabBoxClient *under) override;
+    void shadeClient(TabBoxClient *c, bool b) const override;
+    QWeakPointer< TabBoxClient > clientToAddToList(KWin::TabBox::TabBoxClient* client, int desktop) const override;
+    QWeakPointer< TabBoxClient > desktopClient() const override;
+    void activateAndClose() override;
     void highlightWindows(TabBoxClient *window = nullptr, QWindow *controller = nullptr) override;
     bool noModifierGrab() const override;
 
@@ -90,19 +90,19 @@
 {
 public:
     explicit TabBoxClientImpl(AbstractClient *client);
-    virtual ~TabBoxClientImpl();
-
-    virtual QString caption() const;
-    virtual QIcon icon() const override;
-    virtual WId window() const;
-    virtual bool isMinimized() const;
-    virtual int x() const;
-    virtual int y() const;
-    virtual int width() const;
-    virtual int height() const;
-    virtual bool isCloseable() const;
-    virtual void close();
-    virtual bool isFirstInTabBox() const;
+    ~TabBoxClientImpl() override;
+
+    QString caption() const override;
+    QIcon icon() const override;
+    WId window() const override;
+    bool isMinimized() const override;
+    int x() const override;
+    int y() const override;
+    int width() const override;
+    int height() const override;
+    bool isCloseable() const override;
+    void close() override;
+    bool isFirstInTabBox() const override;
 
     AbstractClient* client() const {
         return m_client;