diff --git a/src/plugins/debugger/debuggermainwindow.h b/src/plugins/debugger/debuggermainwindow.h
index 8ebc099cccd2e9be4134f2c31a30287ec8d51476..536cba8f95589d42717804ac9ba12d51693643d4 100644
--- a/src/plugins/debugger/debuggermainwindow.h
+++ b/src/plugins/debugger/debuggermainwindow.h
@@ -4,8 +4,7 @@
 #include "debuggeruiswitcher.h"
 #include <utils/fancymainwindow.h>
 
-
-class QMenu;
+QT_FORWARD_DECLARE_CLASS(QMenu);
 
 namespace Debugger {
 
diff --git a/src/plugins/debugger/debuggeruiswitcher.h b/src/plugins/debugger/debuggeruiswitcher.h
index 85e09af9d66df5ee381668717e2742e59c8fae4c..7ace45b40effb407d3f1a78897d71c0bb98b3261 100644
--- a/src/plugins/debugger/debuggeruiswitcher.h
+++ b/src/plugins/debugger/debuggeruiswitcher.h
@@ -13,10 +13,10 @@ namespace Core {
     class Command;
 }
 
-class QAction;
-class QDockWidget;
-class QStackedWidget;
-class QComboBox;
+QT_FORWARD_DECLARE_CLASS(Action);
+QT_FORWARD_DECLARE_CLASS(QDockWidget);
+QT_FORWARD_DECLARE_CLASS(QStackedWidget);
+QT_FORWARD_DECLARE_CLASS(QComboBox);
 
 namespace Debugger {
     class DebuggerMainWindow;
diff --git a/src/plugins/qmldesigner/components/itemlibrary/itemlibrarymodel.h b/src/plugins/qmldesigner/components/itemlibrary/itemlibrarymodel.h
index 22a1beef7aab00b6eccdf75c007d6fa23eaaffec..07c51ccdd56a006373e8d4fffc751dfa4b5d2269 100644
--- a/src/plugins/qmldesigner/components/itemlibrary/itemlibrarymodel.h
+++ b/src/plugins/qmldesigner/components/itemlibrary/itemlibrarymodel.h
@@ -7,7 +7,7 @@
 #include <QScriptEngine>
 #include <private/qmllistmodel_p.h>
 
-class QMimeData;
+QT_FORWARD_DECLARE_CLASS(QMimeData);
 
 namespace QmlDesigner {
 
diff --git a/src/plugins/qmldesigner/components/itemlibrary/itemlibrarytreeview.h b/src/plugins/qmldesigner/components/itemlibrary/itemlibrarytreeview.h
index 61edc0367ce2e5127931e51a7b874ce737ea36a6..a041f063878a4b9c1759de6a071e1fcc1cb42cc0 100644
--- a/src/plugins/qmldesigner/components/itemlibrary/itemlibrarytreeview.h
+++ b/src/plugins/qmldesigner/components/itemlibrary/itemlibrarytreeview.h
@@ -36,7 +36,7 @@
 #include <QDebug>
 #include <QTimeLine>
 
-class QLabel;
+QT_FORWARD_DECLARE_CLASS(QLabel);
 
 namespace QmlDesigner {
 
diff --git a/src/plugins/qmlinspector/inspectoroutputpane.h b/src/plugins/qmlinspector/inspectoroutputpane.h
index e1add1ff032ed04c9cbee32389cb0d5ce1210fb6..0bc53d323120cb2ff0d0475b90e5565e57b23a87 100644
--- a/src/plugins/qmlinspector/inspectoroutputpane.h
+++ b/src/plugins/qmlinspector/inspectoroutputpane.h
@@ -33,8 +33,8 @@
 
 #include <QtCore/QObject>
 
-class QTextEdit;
-class RunControl;
+QT_FORWARD_DECLARE_CLASS(QTextEdit);
+QT_FORWARD_DECLARE_CLASS(RunControl);
 
 namespace Qml {
 
diff --git a/src/plugins/qmlinspector/qmlinspector.h b/src/plugins/qmlinspector/qmlinspector.h
index d9a8eddde923da2178f484e83c6d810a4a51ffcd..8db7b233a617ee8ab3894822f8b0f007fea9654a 100644
--- a/src/plugins/qmlinspector/qmlinspector.h
+++ b/src/plugins/qmlinspector/qmlinspector.h
@@ -55,6 +55,7 @@ class ObjectPropertiesView;
 class CanvasFrameRate;
 class ExpressionQueryWidget;
 
+QT_END_NAMESPACE
 
 namespace Qml {
     class EngineSpinBox;
@@ -112,6 +113,4 @@ private:
 
 }
 
-QT_END_NAMESPACE
-
 #endif
diff --git a/src/plugins/qmlinspector/qmlinspectorplugin.h b/src/plugins/qmlinspector/qmlinspectorplugin.h
index 77f17d05ab86c9fcb6a7488c75385786c004c5bf..5625e2d1a819b5b5fb2576180031db66abac5272 100644
--- a/src/plugins/qmlinspector/qmlinspectorplugin.h
+++ b/src/plugins/qmlinspector/qmlinspectorplugin.h
@@ -35,18 +35,16 @@
 #include <QtCore/QPointer>
 #include <QtCore/QTimer>
 
-QT_BEGIN_NAMESPACE
+QT_FORWARD_DECLARE_CLASS(QStringList);
 
-class QStringList;
+namespace Core {
+    class IMode;
+}
 
 namespace ProjectExplorer {
     class Project;
 }
 
-namespace Core {
-    class IMode;
-}
-
 namespace Qml {
     class QmlInspector;
     class InspectorOutputPane;
@@ -83,6 +81,4 @@ private:
 
 }
 
-QT_END_NAMESPACE
-
 #endif // QMLINSPECTORPLUGIN_H