diff --git a/src/lib/3rdparty/lineedit.h b/src/lib/3rdparty/lineedit.h
index f84fd450f..f47d4353c 100644
--- a/src/lib/3rdparty/lineedit.h
+++ b/src/lib/3rdparty/lineedit.h
@@ -106,7 +106,7 @@ public:
     int minHeight() const;
     void setMinHeight(int height);
 
-    QSize sizeHint() const;
+    QSize sizeHint() const override;
     QAction* editAction(EditAction action) const;
 
 public slots:
@@ -114,12 +114,12 @@ public slots:
     void updateTextMargins();
 
 protected:
-    void focusInEvent(QFocusEvent* event);
-    void mousePressEvent(QMouseEvent* event);
-    void mouseReleaseEvent(QMouseEvent* event);
-    void mouseDoubleClickEvent(QMouseEvent* event);
+    void focusInEvent(QFocusEvent* event) override;
+    void mousePressEvent(QMouseEvent* event) override;
+    void mouseReleaseEvent(QMouseEvent* event) override;
+    void mouseDoubleClickEvent(QMouseEvent* event) override;
     void resizeEvent(QResizeEvent *event) override;
-    bool event(QEvent* event);
+    bool event(QEvent* event) override;
 
     QMenu* createContextMenu();
 
diff --git a/src/lib/adblock/adblockplugin.h b/src/lib/adblock/adblockplugin.h
index 129ff8d4d..db7e7c5f5 100644
--- a/src/lib/adblock/adblockplugin.h
+++ b/src/lib/adblock/adblockplugin.h
@@ -28,10 +28,10 @@ class AdBlockPlugin : public QObject, public PluginInterface
 
 public:
     explicit AdBlockPlugin();
-    PluginSpec pluginSpec();
-    void init(InitState state, const QString &settingsPath);
-    void unload();
-    bool testPlugin();
+    PluginSpec pluginSpec() override;
+    void init(InitState state, const QString &settingsPath) override;
+    void unload() override;
+    bool testPlugin() override;
 
 private:
     void webPageCreated(WebPage *page);
diff --git a/src/lib/bookmarks/bookmarkstoolbarbutton.h b/src/lib/bookmarks/bookmarkstoolbarbutton.h
index 3de83c083..07a83c8cc 100644
--- a/src/lib/bookmarks/bookmarkstoolbarbutton.h
+++ b/src/lib/bookmarks/bookmarkstoolbarbutton.h
@@ -63,11 +63,11 @@ private:
     void init();
     QString createTooltip() const;
 
-    void enterEvent(QEvent* event);
-    void leaveEvent(QEvent* event);
-    void mousePressEvent(QMouseEvent* event);
-    void mouseReleaseEvent(QMouseEvent* event);
-    void paintEvent(QPaintEvent* event);
+    void enterEvent(QEvent* event) override;
+    void leaveEvent(QEvent* event) override;
+    void mousePressEvent(QMouseEvent* event) override;
+    void mouseReleaseEvent(QMouseEvent* event) override;
+    void paintEvent(QPaintEvent* event) override;
 
     BookmarkItem* m_bookmark;
     BrowserWindow* m_window;
diff --git a/src/lib/downloads/downloadmanager.h b/src/lib/downloads/downloadmanager.h
index 882175cfa..1ce3f8952 100644
--- a/src/lib/downloads/downloadmanager.h
+++ b/src/lib/downloads/downloadmanager.h
@@ -90,10 +90,10 @@ signals:
 
 private:
     void showEvent(QShowEvent *event) override;
-    void timerEvent(QTimerEvent* e);
-    void closeEvent(QCloseEvent* e);
-    void resizeEvent(QResizeEvent* e);
-    void keyPressEvent(QKeyEvent* e);
+    void timerEvent(QTimerEvent* e) override;
+    void closeEvent(QCloseEvent* e) override;
+    void resizeEvent(QResizeEvent* e) override;
+    void keyPressEvent(QKeyEvent* e) override;
 
     void closeDownloadTab(const QUrl &url) const;
 
diff --git a/src/lib/opensearch/searchenginesdialog.h b/src/lib/opensearch/searchenginesdialog.h
index 4bb82bcf7..70a197f0e 100644
--- a/src/lib/opensearch/searchenginesdialog.h
+++ b/src/lib/opensearch/searchenginesdialog.h
@@ -39,7 +39,7 @@ public:
     ~SearchEnginesDialog();
 
 public slots:
-    void accept();
+    void accept() override;
 
 private slots:
     void addEngine();
diff --git a/src/lib/popupwindow/popupwindow.h b/src/lib/popupwindow/popupwindow.h
index 85b4bb707..671bda11d 100644
--- a/src/lib/popupwindow/popupwindow.h
+++ b/src/lib/popupwindow/popupwindow.h
@@ -59,7 +59,7 @@ private slots:
     void searchOnPage();
 
 private:
-    void closeEvent(QCloseEvent* event);
+    void closeEvent(QCloseEvent *event) override;
     void resizeEvent(QResizeEvent *event) override;
 
     PopupWebView* m_view;
diff --git a/src/plugins/GreaseMonkey/gm_plugin.h b/src/plugins/GreaseMonkey/gm_plugin.h
index bf984586b..a1368ddbc 100644
--- a/src/plugins/GreaseMonkey/gm_plugin.h
+++ b/src/plugins/GreaseMonkey/gm_plugin.h
@@ -31,14 +31,12 @@ class GM_Plugin : public QObject, public PluginInterface
 
 public:
     explicit GM_Plugin();
-    PluginSpec pluginSpec();
-
-    void init(InitState state, const QString &settingsPath);
-    void unload();
-    bool testPlugin();
-
-    QTranslator* getTranslator(const QString &locale);
-    void showSettings(QWidget* parent = 0);
+    PluginSpec pluginSpec() override;
+    void init(InitState state, const QString &settingsPath) override;
+    void unload() override;
+    bool testPlugin() override;
+    QTranslator* getTranslator(const QString &locale) override;
+    void showSettings(QWidget* parent = 0) override;
 
     bool acceptNavigationRequest(WebPage *page, const QUrl &url, QWebEnginePage::NavigationType type, bool isMainFrame) override;
 
diff --git a/src/plugins/VerticalTabs/tabfiltermodel.h b/src/plugins/VerticalTabs/tabfiltermodel.h
index cb6676cbc..b8976dac7 100644
--- a/src/plugins/VerticalTabs/tabfiltermodel.h
+++ b/src/plugins/VerticalTabs/tabfiltermodel.h
@@ -33,7 +33,7 @@ public:
     void setRejectDropOnLastIndex(bool reject);
 
 private:
-    bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const;
+    bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const override;
     bool canDropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent) const override;
 
     enum Mode {