diff --git a/src/corelib/io/qfilesystemwatcher_polling_p.h b/src/corelib/io/qfilesystemwatcher_polling_p.h
index 14f6345412..e50082c6d3 100644
--- a/src/corelib/io/qfilesystemwatcher_polling_p.h
+++ b/src/corelib/io/qfilesystemwatcher_polling_p.h
@@ -58,6 +58,7 @@
 #include <QtCore/qdatetime.h>
 #include <QtCore/qdir.h>
 #include <QtCore/qtimer.h>
+#include <QtCore/qhash.h>
 
 #include "qfilesystemwatcher_p.h"
 
diff --git a/src/corelib/kernel/qeventdispatcher_win_p.h b/src/corelib/kernel/qeventdispatcher_win_p.h
index c404967e6a..a831ad39e8 100644
--- a/src/corelib/kernel/qeventdispatcher_win_p.h
+++ b/src/corelib/kernel/qeventdispatcher_win_p.h
@@ -55,6 +55,7 @@
 
 #include "QtCore/qabstracteventdispatcher.h"
 #include "QtCore/qt_windows.h"
+#include "QtCore/qhash.h"
 
 #include "qabstracteventdispatcher_p.h"
 
diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index 8fa5dcdcff..2231518253 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -69,6 +69,16 @@
 
 QT_BEGIN_NAMESPACE
 
+struct QObjectPrivate::ExtraData
+{
+    ExtraData() {}
+#ifndef QT_NO_USERDATA
+    QVector<QObjectUserData *> userData;
+#endif
+    QList<QByteArray> propertyNames;
+    QList<QVariant> propertyValues;
+};
+
 static int DIRECT_CONNECTION_ONLY = 0;
 
 static int *queuedConnectionTypes(const QList<QByteArray> &typeNames)
diff --git a/src/corelib/kernel/qobject_p.h b/src/corelib/kernel/qobject_p.h
index fa1aee8173..f75d4464b2 100644
--- a/src/corelib/kernel/qobject_p.h
+++ b/src/corelib/kernel/qobject_p.h
@@ -60,7 +60,6 @@
 #include "QtCore/qlist.h"
 #include "QtCore/qvector.h"
 #include "QtCore/qreadwritelock.h"
-#include "QtCore/qvariant.h"
 
 QT_BEGIN_NAMESPACE
 
@@ -98,16 +97,8 @@ class Q_CORE_EXPORT QObjectPrivate : public QObjectData
 {
     Q_DECLARE_PUBLIC(QObject)
 
+    struct ExtraData;
 public:
-    struct ExtraData
-    {
-        ExtraData() {}
-#ifndef QT_NO_USERDATA
-        QVector<QObjectUserData *> userData;
-#endif
-        QList<QByteArray> propertyNames;
-        QList<QVariant> propertyValues;
-    };
 
     typedef void (*StaticMetaCallFunction)(QObject *, QMetaObject::Call, int, void **);
     struct Connection
diff --git a/src/gui/kernel/qopenglcontext_p.h b/src/gui/kernel/qopenglcontext_p.h
index 3e2c35f088..d5c4d6c762 100644
--- a/src/gui/kernel/qopenglcontext_p.h
+++ b/src/gui/kernel/qopenglcontext_p.h
@@ -49,9 +49,7 @@
 #include <private/qobject_p.h>
 #include <qmutex.h>
 
-#ifndef QT_NO_DEBUG
 #include <QtCore/QHash>
-#endif
 
 QT_BEGIN_HEADER