diff --git a/src/plugins/projectexplorer/projectexplorer.cpp b/src/plugins/projectexplorer/projectexplorer.cpp
index e3125bd7a23..469d9b9b2f9 100644
--- a/src/plugins/projectexplorer/projectexplorer.cpp
+++ b/src/plugins/projectexplorer/projectexplorer.cpp
@@ -697,7 +697,6 @@ public:
     SshSettingsPage m_sshSettingsPage;
     CustomParsersSettingsPage m_customParsersSettingsPage;
 
-    ProjectTreeWidgetFactory m_projectTreeFactory;
     DefaultDeployConfigurationFactory m_defaultDeployConfigFactory;
 
     IDocumentFactory m_documentFactory;
@@ -816,6 +815,8 @@ bool ProjectExplorerPlugin::initialize(const QStringList &arguments, QString *er
     setupMsvcToolchain();
     setupClangClToolchain();
 
+    setupProjectTreeWidgetFactory();
+
     dd = new ProjectExplorerPluginPrivate;
 
     dd->extendFolderNavigationWidgetFactory();
diff --git a/src/plugins/projectexplorer/projecttreewidget.cpp b/src/plugins/projectexplorer/projecttreewidget.cpp
index c63dc87a51f..774a8bb1604 100644
--- a/src/plugins/projectexplorer/projecttreewidget.cpp
+++ b/src/plugins/projectexplorer/projecttreewidget.cpp
@@ -14,11 +14,12 @@
 #include <coreplugin/actionmanager/actionmanager.h>
 #include <coreplugin/actionmanager/command.h>
 #include <coreplugin/documentmanager.h>
-#include <coreplugin/icore.h>
-#include <coreplugin/idocument.h>
 #include <coreplugin/editormanager/editormanager.h>
 #include <coreplugin/editormanager/ieditor.h>
 #include <coreplugin/find/itemviewfind.h>
+#include <coreplugin/icore.h>
+#include <coreplugin/idocument.h>
+#include <coreplugin/inavigationwidgetfactory.h>
 
 #include <utils/algorithm.h>
 #include <utils/navigationtreeview.h>
@@ -46,9 +47,9 @@ using namespace Utils;
 
 QList<ProjectTreeWidget *> ProjectTreeWidget::m_projectTreeWidgets;
 
-namespace {
+namespace ProjectExplorer::Internal {
 
-class ProjectTreeItemDelegate : public QStyledItemDelegate
+class ProjectTreeItemDelegate final : public QStyledItemDelegate
 {
 public:
     ProjectTreeItemDelegate(QTreeView *view) : QStyledItemDelegate(view),
@@ -65,12 +66,12 @@ public:
                 this, &ProjectTreeItemDelegate::deleteAllIndicators);
     }
 
-    ~ProjectTreeItemDelegate() override
+    ~ProjectTreeItemDelegate() final
     {
         deleteAllIndicators();
     }
 
-    void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const override
+    void paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const final
     {
         const bool useUnavailableMarker = index.data(Project::UseUnavailableMarkerRole).toBool();
         if (useUnavailableMarker) {
@@ -128,7 +129,6 @@ private:
 };
 
 bool debug = false;
-}
 
 class ProjectTreeView : public NavigationTreeView
 {
@@ -159,7 +159,7 @@ public:
         m_cachedSize = -1;
     }
 
-    void setModel(QAbstractItemModel *newModel) override
+    void setModel(QAbstractItemModel *newModel) final
     {
         // Note: Don't connect to column signals, as we have only one column
         if (model()) {
@@ -194,7 +194,7 @@ public:
         NavigationTreeView::setModel(newModel);
     }
 
-    int sizeHintForColumn(int column) const override
+    int sizeHintForColumn(int column) const final
     {
         if (m_cachedSize < 0)
             m_cachedSize = NavigationTreeView::sizeHintForColumn(column);
@@ -211,7 +211,7 @@ private:
 
   Shows the projects in form of a tree.
   */
-ProjectTreeWidget::ProjectTreeWidget(QWidget *parent) : QWidget(parent)
+ProjectTreeWidget::ProjectTreeWidget()
 {
     // We keep one instance per tree as this also manages the
     // simple/non-simple etc state which is per tree.
@@ -614,20 +614,26 @@ bool ProjectTreeWidget::projectFilter()
     return m_model->projectFilterEnabled();
 }
 
-
-ProjectTreeWidgetFactory::ProjectTreeWidgetFactory()
+class ProjectTreeWidgetFactory final : public INavigationWidgetFactory
 {
-    setDisplayName(Tr::tr("Projects"));
-    setPriority(100);
-    setId(ProjectExplorer::Constants::PROJECTTREE_ID);
-    setActivationSequence(QKeySequence(useMacShortcuts ? Tr::tr("Meta+X") : Tr::tr("Alt+X")));
-}
+public:
+    ProjectTreeWidgetFactory()
+    {
+        setDisplayName(Tr::tr("Projects"));
+        setPriority(100);
+        setId(ProjectExplorer::Constants::PROJECTTREE_ID);
+        setActivationSequence(QKeySequence(useMacShortcuts ? Tr::tr("Meta+X") : Tr::tr("Alt+X")));
+    }
 
-NavigationView ProjectTreeWidgetFactory::createWidget()
-{
-    auto ptw = new ProjectTreeWidget;
-    return {ptw, ptw->createToolButtons()};
-}
+    Core::NavigationView createWidget() final
+    {
+        auto ptw = new ProjectTreeWidget;
+        return {ptw, ptw->createToolButtons()};
+    }
+
+    void restoreSettings(Utils::QtcSettings *settings, int position, QWidget *widget) final;
+    void saveSettings(Utils::QtcSettings *settings, int position, QWidget *widget) final;
+};
 
 const bool kProjectFilterDefault = false;
 const bool kHideGeneratedFilesDefault = true;
@@ -683,3 +689,10 @@ void ProjectTreeWidgetFactory::restoreSettings(QtcSettings *settings, int positi
         settings->value(baseKey + kHideSourceGroupsKey, kHideSourceGroupsDefault).toBool());
     ptw->setAutoSynchronization(settings->value(baseKey + kSyncKey, kSyncDefault).toBool());
 }
+
+void setupProjectTreeWidgetFactory()
+{
+    static ProjectTreeWidgetFactory theProjectTreeWidgetFactory;
+}
+
+} // ProjectExplorer::Internal
diff --git a/src/plugins/projectexplorer/projecttreewidget.h b/src/plugins/projectexplorer/projecttreewidget.h
index c6c2cad2d1a..50844e53384 100644
--- a/src/plugins/projectexplorer/projecttreewidget.h
+++ b/src/plugins/projectexplorer/projecttreewidget.h
@@ -3,14 +3,15 @@
 
 #pragma once
 
-#include <coreplugin/inavigationwidgetfactory.h>
-
 #include <utils/filepath.h>
 
-#include <QWidget>
 #include <QModelIndex>
+#include <QWidget>
 
-QT_FORWARD_DECLARE_CLASS(QTreeView)
+QT_BEGIN_NAMESPACE
+class QToolButton;
+class QTreeView;
+QT_END_NAMESPACE
 
 namespace ProjectExplorer {
 
@@ -20,12 +21,12 @@ namespace Internal {
 
 class FlatModel;
 
-class ProjectTreeWidget : public QWidget
+class ProjectTreeWidget final : public QWidget
 {
     Q_OBJECT
 public:
-    explicit ProjectTreeWidget(QWidget *parent = nullptr);
-    ~ProjectTreeWidget() override;
+    ProjectTreeWidget();
+    ~ProjectTreeWidget() final;
 
     bool autoSynchronization() const;
     void setAutoSynchronization(bool sync);
@@ -85,16 +86,7 @@ private:
     friend class ProjectTreeWidgetFactory;
 };
 
-class ProjectTreeWidgetFactory : public Core::INavigationWidgetFactory
-{
-    Q_OBJECT
-public:
-    ProjectTreeWidgetFactory();
-
-    Core::NavigationView createWidget() override;
-    void restoreSettings(Utils::QtcSettings *settings, int position, QWidget *widget) override;
-    void saveSettings(Utils::QtcSettings *settings, int position, QWidget *widget) override;
-};
+void setupProjectTreeWidgetFactory();
 
 } // namespace Internal
 } // namespace ProjectExplorer