diff --git a/containments/desktop/plugins/folder/directorypicker.cpp b/containments/desktop/plugins/folder/directorypicker.cpp
--- a/containments/desktop/plugins/folder/directorypicker.cpp
+++ b/containments/desktop/plugins/folder/directorypicker.cpp
@@ -42,7 +42,7 @@
 void DirectoryPicker::open()
 {
     if (!m_dialog) {
-        m_dialog = new QFileDialog(0, i18n("Select Folder"),
+        m_dialog = new QFileDialog(nullptr, i18n("Select Folder"),
             QStandardPaths::standardLocations(QStandardPaths::HomeLocation).at(0));
         m_dialog->setFileMode(QFileDialog::Directory);
         m_dialog->setOption(QFileDialog::ShowDirsOnly, true);
diff --git a/containments/desktop/plugins/folder/foldermodel.h b/containments/desktop/plugins/folder/foldermodel.h
--- a/containments/desktop/plugins/folder/foldermodel.h
+++ b/containments/desktop/plugins/folder/foldermodel.h
@@ -125,7 +125,7 @@
         explicit FolderModel(QObject *parent = nullptr);
         ~FolderModel();
 
-        QHash<int, QByteArray> roleNames() const Q_DECL_OVERRIDE;
+        QHash<int, QByteArray> roleNames() const override;
         static QHash<int, QByteArray> staticRoleNames();
 
         QString url() const;
@@ -216,11 +216,11 @@
 
         Q_INVOKABLE void linkHere(const QUrl &sourceUrl);
 
-        QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const Q_DECL_OVERRIDE;
+        QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
         int indexForUrl(const QUrl &url) const;
         KFileItem itemForIndex(const QModelIndex &index) const;
         bool isDir(const QModelIndex &index, const KDirModel *dirModel) const;
-        bool lessThan(const QModelIndex &left, const QModelIndex &right) const Q_DECL_OVERRIDE;
+        bool lessThan(const QModelIndex &left, const QModelIndex &right) const override;
         Qt::DropActions supportedDragActions() const override;
 
         Q_INVOKABLE void paste();
@@ -257,7 +257,7 @@
         void popupMenuAboutToShow(KIO::DropJob *dropJob, QMimeData *mimeData, int x, int y);
 
     protected:
-        bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const Q_DECL_OVERRIDE;
+        bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const override;
         bool matchMimeType(const KFileItem &item) const;
         bool matchPattern(const KFileItem &item) const;
 
diff --git a/containments/desktop/plugins/folder/foldermodel.cpp b/containments/desktop/plugins/folder/foldermodel.cpp
--- a/containments/desktop/plugins/folder/foldermodel.cpp
+++ b/containments/desktop/plugins/folder/foldermodel.cpp
@@ -96,11 +96,11 @@
     m_dirWatch(nullptr),
     m_dragInProgress(false),
     m_urlChangedWhileDragging(false),
-    m_previewGenerator(0),
-    m_viewAdapter(0),
+    m_previewGenerator(nullptr),
+    m_viewAdapter(nullptr),
     m_actionCollection(this),
-    m_newMenu(0),
-    m_fileItemActions(0),
+    m_newMenu(nullptr),
+    m_fileItemActions(nullptr),
     m_usedByContainment(false),
     m_locked(true),
     m_sortMode(0),
@@ -115,7 +115,7 @@
     qmlRegisterType<KIO::DropJob>();
     DirLister *dirLister = new DirLister(this);
     dirLister->setDelayedMimeTypes(true);
-    dirLister->setAutoErrorHandlingEnabled(false, 0);
+    dirLister->setAutoErrorHandlingEnabled(false, nullptr);
     connect(dirLister, &DirLister::error, this, &FolderModel::dirListFailed);
     connect(dirLister, &KCoreDirLister::itemsDeleted, this, &FolderModel::evictFromIsDirCache);
 
@@ -210,6 +210,7 @@
 
     if (m_dirWatch) {
         delete m_dirWatch;
+        m_dirWatch = nullptr;
     }
 
     if (resolvedUrl.isValid()) {
@@ -235,7 +236,7 @@
 {
     QUrl resolvedUrl;
 
-    if (url.startsWith('~')) {
+    if (url.startsWith(QLatin1Char('~'))) {
         resolvedUrl = QUrl::fromLocalFile(KShell::tildeExpand(url));
     } else {
         resolvedUrl = QUrl::fromUserInput(url);
@@ -482,7 +483,7 @@
     m_filterPattern = pattern;
     m_filterPatternMatchAll = (pattern == QLatin1String("*"));
 
-    const QStringList patterns = pattern.split(' ');
+    const QStringList patterns = pattern.split(QLatin1Char(' '));
     m_regExps.clear();
     m_regExps.reserve(patterns.count());
 
@@ -569,7 +570,7 @@
         url.setScheme(QStringLiteral("file"));
     }
 
-    KRun *run = new KRun(url, 0);
+    KRun *run = new KRun(url, nullptr);
     // On desktop:/ we want to be able to run .desktop files right away,
     // otherwise ask for security reasons. We also don't use the targetUrl()
     // from above since we don't want the resolved /home/foo/Desktop URL.
@@ -1027,7 +1028,7 @@
     QVector<int> roles;
     roles.append(SelectedRole);
 
-    foreach(const QModelIndex index, indices) {
+    foreach(const QModelIndex &index, indices) {
         emit dataChanged(index, index, roles);
     }
 
@@ -1355,7 +1356,7 @@
     m_newMenu = new KNewFileMenu(&m_actionCollection, QStringLiteral("newMenu"), QApplication::desktop());
     m_newMenu->setModal(false);
 
-    m_copyToMenu = new KFileCopyToMenu(Q_NULLPTR);
+    m_copyToMenu = new KFileCopyToMenu(nullptr);
 }
 
 QAction* FolderModel::action(const QString &name) const
@@ -1538,7 +1539,7 @@
             QAction *act = new QAction(menu);
             act->setText(i18n("&Properties"));
             QObject::connect(act, &QAction::triggered, [this, items]() {
-                    KPropertiesDialog::showDialog(items, Q_NULLPTR, false /*non modal*/);
+                    KPropertiesDialog::showDialog(items, nullptr, false /*non modal*/);
             });
             menu->addAction(act);
         }
@@ -1655,7 +1656,7 @@
 
     const QList<QUrl> urls = selectedUrls(false);
     for (const QUrl &url : urls) {
-        (void) new KRun(url, Q_NULLPTR);
+        (void) new KRun(url, nullptr);
     }
 }
 
diff --git a/containments/desktop/plugins/folder/labelgenerator.cpp b/containments/desktop/plugins/folder/labelgenerator.cpp
--- a/containments/desktop/plugins/folder/labelgenerator.cpp
+++ b/containments/desktop/plugins/folder/labelgenerator.cpp
@@ -126,14 +126,14 @@
             label = label.right(label.length() - root.length());
 
             if (!label.isEmpty()) {
-                if (label.at(0) == '/') {
+                if (label.at(0) == QLatin1Char('/')) {
                     label.remove(0, 1);
                 }
 
                 if (m_rtl) {
-                    label.prepend(" < ");
+                    label.prepend(QStringLiteral(" < "));
                 } else {
-                    label.prepend(" > ");
+                    label.prepend(QStringLiteral(" > "));
                 }
             }
 
diff --git a/containments/desktop/plugins/folder/mimetypesmodel.h b/containments/desktop/plugins/folder/mimetypesmodel.h
--- a/containments/desktop/plugins/folder/mimetypesmodel.h
+++ b/containments/desktop/plugins/folder/mimetypesmodel.h
@@ -36,12 +36,12 @@
         ~MimeTypesModel();
 
         QHash<int, QByteArray> roleNames() const override;
-        QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const Q_DECL_OVERRIDE;
-        bool setData(const QModelIndex &index, const QVariant &value, int role) Q_DECL_OVERRIDE;
+        QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
+        bool setData(const QModelIndex &index, const QVariant &value, int role) override;
 
         Q_INVOKABLE void checkAll();
 
-        int rowCount(const QModelIndex &parent = QModelIndex()) const Q_DECL_OVERRIDE { Q_UNUSED(parent) return m_mimeTypesList.size(); }
+        int rowCount(const QModelIndex &parent = QModelIndex()) const override { Q_UNUSED(parent) return m_mimeTypesList.size(); }
 
         QStringList checkedTypes() const;
         void setCheckedTypes(const QStringList &list);
diff --git a/containments/desktop/plugins/folder/placesmodel.h b/containments/desktop/plugins/folder/placesmodel.h
--- a/containments/desktop/plugins/folder/placesmodel.h
+++ b/containments/desktop/plugins/folder/placesmodel.h
@@ -44,7 +44,7 @@
         void placesChanged() const;
 
     protected:
-        bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const Q_DECL_OVERRIDE;
+        bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const override;
 
     private:
         KFilePlacesModel *m_sourceModel;
diff --git a/containments/desktop/plugins/folder/positioner.h b/containments/desktop/plugins/folder/positioner.h
--- a/containments/desktop/plugins/folder/positioner.h
+++ b/containments/desktop/plugins/folder/positioner.h
@@ -49,7 +49,7 @@
         void setPerStripe(int perStripe);
 
         QStringList positions() const;
-        void setPositions(QStringList positions);
+        void setPositions(const QStringList &positions);
 
         Q_INVOKABLE int map(int row) const;
 
@@ -66,13 +66,13 @@
 
         QHash<int, QByteArray> roleNames() const Q_DECL_OVERRIDE;
 
-        QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const Q_DECL_OVERRIDE;
+        QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const override;
         QModelIndex parent(const QModelIndex &index) const Q_DECL_OVERRIDE;
 
-        QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const Q_DECL_OVERRIDE;
+        QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
 
-        int rowCount(const QModelIndex &parent = QModelIndex()) const Q_DECL_OVERRIDE;
-        int columnCount(const QModelIndex &parent = QModelIndex()) const Q_DECL_OVERRIDE;
+        int rowCount(const QModelIndex &parent = QModelIndex()) const override;
+        int columnCount(const QModelIndex &parent = QModelIndex()) const override;
 
     Q_SIGNALS:
         void enabledChanged() const;
diff --git a/containments/desktop/plugins/folder/positioner.cpp b/containments/desktop/plugins/folder/positioner.cpp
--- a/containments/desktop/plugins/folder/positioner.cpp
+++ b/containments/desktop/plugins/folder/positioner.cpp
@@ -121,7 +121,7 @@
     return m_positions;
 }
 
-void Positioner::setPositions(QStringList positions)
+void Positioner::setPositions(const QStringList &positions)
 {
     if (m_positions != positions) {
         m_positions = positions;
diff --git a/containments/desktop/plugins/folder/previewpluginsmodel.h b/containments/desktop/plugins/folder/previewpluginsmodel.h
--- a/containments/desktop/plugins/folder/previewpluginsmodel.h
+++ b/containments/desktop/plugins/folder/previewpluginsmodel.h
@@ -37,10 +37,10 @@
         ~PreviewPluginsModel();
 
         QHash<int, QByteArray> roleNames() const override;
-        QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const Q_DECL_OVERRIDE;
-        bool setData(const QModelIndex &index, const QVariant &value, int role) Q_DECL_OVERRIDE;
+        QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
+        bool setData(const QModelIndex &index, const QVariant &value, int role) override;
 
-        int rowCount(const QModelIndex &parent = QModelIndex()) const Q_DECL_OVERRIDE { Q_UNUSED(parent) return m_plugins.size(); }
+        int rowCount(const QModelIndex &parent = QModelIndex()) const override { Q_UNUSED(parent) return m_plugins.size(); }
 
         QStringList checkedPlugins() const;
         void setCheckedPlugins(const QStringList &list);
diff --git a/containments/desktop/plugins/folder/previewpluginsmodel.cpp b/containments/desktop/plugins/folder/previewpluginsmodel.cpp
--- a/containments/desktop/plugins/folder/previewpluginsmodel.cpp
+++ b/containments/desktop/plugins/folder/previewpluginsmodel.cpp
@@ -109,7 +109,7 @@
 QStringList PreviewPluginsModel::checkedPlugins() const
 {
     QStringList list;
-    for (int i =0; i < m_checkedRows.size(); ++i) {
+    for (int i = 0; i < m_checkedRows.size(); ++i) {
         if (m_checkedRows.at(i)) {
             list.append(m_plugins.at(i)->desktopEntryName());
         }
diff --git a/containments/desktop/plugins/folder/rubberband.h b/containments/desktop/plugins/folder/rubberband.h
--- a/containments/desktop/plugins/folder/rubberband.h
+++ b/containments/desktop/plugins/folder/rubberband.h
@@ -30,12 +30,12 @@
         explicit RubberBand(QQuickItem *parent = nullptr);
         ~RubberBand();
 
-        void paint(QPainter* painter) Q_DECL_OVERRIDE;
+        void paint(QPainter* painter) override;
 
         Q_INVOKABLE bool intersects(const QRectF &rect);
 
     protected:
-        void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry) Q_DECL_OVERRIDE;
+        void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry) override;
 
     private:
         QRectF m_geometry;
diff --git a/containments/desktop/plugins/folder/shortcut.h b/containments/desktop/plugins/folder/shortcut.h
--- a/containments/desktop/plugins/folder/shortcut.h
+++ b/containments/desktop/plugins/folder/shortcut.h
@@ -49,7 +49,7 @@
     void moveToTrash();
 
 protected:
-    bool eventFilter(QObject *obj, QEvent *e) Q_DECL_OVERRIDE;
+    bool eventFilter(QObject *obj, QEvent *e) override;
 };
 
 #endif // SHORTCUT_H
diff --git a/containments/desktop/plugins/folder/viewpropertiesmenu.h b/containments/desktop/plugins/folder/viewpropertiesmenu.h
--- a/containments/desktop/plugins/folder/viewpropertiesmenu.h
+++ b/containments/desktop/plugins/folder/viewpropertiesmenu.h
@@ -30,7 +30,7 @@
 {
     Q_OBJECT
 
-    Q_PROPERTY(QObject* menu READ menu CONSTANT);
+    Q_PROPERTY(QObject* menu READ menu CONSTANT)
 
     Q_PROPERTY(bool showLayoutActions READ showLayoutActions WRITE setShowLayoutActions NOTIFY showLayoutActionsChanged)
     Q_PROPERTY(bool showLockAction READ showLockAction WRITE setShowLockAction NOTIFY showLockActionChanged)
@@ -45,7 +45,7 @@
     Q_PROPERTY(int iconSize READ iconSize WRITE setIconSize NOTIFY iconSizeChanged)
 
     public:
-        ViewPropertiesMenu(QObject *parent = 0);
+        explicit ViewPropertiesMenu(QObject *parent = nullptr);
         ~ViewPropertiesMenu();
 
         QObject* menu() const;
diff --git a/containments/desktop/plugins/folder/viewpropertiesmenu.cpp b/containments/desktop/plugins/folder/viewpropertiesmenu.cpp
--- a/containments/desktop/plugins/folder/viewpropertiesmenu.cpp
+++ b/containments/desktop/plugins/folder/viewpropertiesmenu.cpp
@@ -92,7 +92,7 @@
         action->setCheckable(true);
         action->setData(i);
         m_iconSize->addAction(action);
-    };
+    }
 
     m_locked = m_menu->addAction(i18n("Locked"), this, SIGNAL(lockedChanged()));
     m_locked->setCheckable(true);