diff --git a/src/plugins/help/filtersettingspage.cpp b/src/plugins/help/filtersettingspage.cpp
index 23dd1e22ec4..41c1e5bbfc2 100644
--- a/src/plugins/help/filtersettingspage.cpp
+++ b/src/plugins/help/filtersettingspage.cpp
@@ -24,14 +24,15 @@
 ****************************************************************************/
 
 #include "filtersettingspage.h"
+
 #include "helpconstants.h"
 #include "helptr.h"
-
-#include <QtCore/QVersionNumber>
-#include <QtHelp/QHelpFilterEngine>
-#include <QtHelp/QHelpFilterSettingsWidget>
 #include "localhelpmanager.h"
 
+#include <QHelpFilterEngine>
+#include <QHelpFilterSettingsWidget>
+#include <QVersionNumber>
+
 using namespace Help::Internal;
 
 FilterSettingsPage::FilterSettingsPage()
diff --git a/src/plugins/help/helpindexfilter.cpp b/src/plugins/help/helpindexfilter.cpp
index a60a9d3a6d9..69c7d9c06da 100644
--- a/src/plugins/help/helpindexfilter.cpp
+++ b/src/plugins/help/helpindexfilter.cpp
@@ -25,23 +25,20 @@
 
 #include "helpindexfilter.h"
 
-#include "helpicons.h"
 #include "helpmanager.h"
 #include "helptr.h"
-#include "topicchooser.h"
+#include "localhelpmanager.h"
 
 #include <coreplugin/icore.h>
 #include <coreplugin/helpmanager.h>
 #include <extensionsystem/pluginmanager.h>
 #include <utils/utilsicons.h>
 
+#include <QHelpEngine>
+#include <QHelpFilterEngine>
+#include <QHelpLink>
 #include <QIcon>
 
-#include "localhelpmanager.h"
-#include <QtHelp/QHelpEngine>
-#include <QtHelp/QHelpFilterEngine>
-#include <QtHelp/QHelpLink>
-
 using namespace Core;
 using namespace Help;
 using namespace Help::Internal;
diff --git a/src/plugins/help/helpindexfilter.h b/src/plugins/help/helpindexfilter.h
index 5c5520ae102..a6c9a6925d2 100644
--- a/src/plugins/help/helpindexfilter.h
+++ b/src/plugins/help/helpindexfilter.h
@@ -52,7 +52,7 @@ public:
                 QString *newText, int *selectionStart, int *selectionLength) const override;
     void refresh(QFutureInterface<void> &future) override;
 
-    Q_INVOKABLE QStringList allIndices() const;
+    QStringList allIndices() const;
 
 signals:
     void linksActivated(const QMultiMap<QString, QUrl> &links, const QString &key) const;
diff --git a/src/plugins/help/localhelpmanager.h b/src/plugins/help/localhelpmanager.h
index 0a895c1559c..2d98411fcd9 100644
--- a/src/plugins/help/localhelpmanager.h
+++ b/src/plugins/help/localhelpmanager.h
@@ -32,8 +32,10 @@
 #include <QObject>
 #include <QUrl>
 
-QT_FORWARD_DECLARE_CLASS(QHelpFilterEngine)
-QT_FORWARD_DECLARE_CLASS(QHelpEngine)
+QT_BEGIN_NAMESPACE
+class QHelpFilterEngine;
+class QHelpEngine;
+QT_END_NAMESPACE
 
 class BookmarkManager;