diff --git a/src/widgets/dialogs/qdialog.cpp b/src/widgets/dialogs/qdialog.cpp
index 4ba26a90f7..13686f301e 100644
--- a/src/widgets/dialogs/qdialog.cpp
+++ b/src/widgets/dialogs/qdialog.cpp
@@ -80,6 +80,11 @@ static inline int themeDialogType(const QDialog *dialog)
     return -1;
 }
 
+QDialogPrivate::~QDialogPrivate()
+{
+    delete m_platformHelper;
+}
+
 QPlatformDialogHelper *QDialogPrivate::platformHelper() const
 {
     // Delayed creation of the platform, ensuring that
diff --git a/src/widgets/dialogs/qdialog_p.h b/src/widgets/dialogs/qdialog_p.h
index 556bd4ff30..d393cc7a94 100644
--- a/src/widgets/dialogs/qdialog_p.h
+++ b/src/widgets/dialogs/qdialog_p.h
@@ -70,7 +70,7 @@ public:
           rescode(0), resetModalityTo(-1), wasModalitySet(true), eventLoop(0),
           nativeDialogInUse(false), m_platformHelper(0), m_platformHelperCreated(false)
         {}
-    ~QDialogPrivate() { delete m_platformHelper; }
+    ~QDialogPrivate();
 
     QWindow *parentWindow() const;
     bool setNativeDialogVisible(bool visible);
diff --git a/src/widgets/effects/qpixmapfilter.cpp b/src/widgets/effects/qpixmapfilter.cpp
index b21726400f..fee8f83305 100644
--- a/src/widgets/effects/qpixmapfilter.cpp
+++ b/src/widgets/effects/qpixmapfilter.cpp
@@ -1018,6 +1018,15 @@ QPixmapColorizeFilter::QPixmapColorizeFilter(QObject *parent)
     d->alphaBlend = false;
 }
 
+/*!
+    \internal
+*/
+QPixmapColorizeFilter::~QPixmapColorizeFilter()
+{
+    // was inline until Qt 5.6, so essentially
+    // must stay empty until ### Qt 6
+}
+
 /*!
     Gets the color of the colorize filter.
 
diff --git a/src/widgets/effects/qpixmapfilter_p.h b/src/widgets/effects/qpixmapfilter_p.h
index 6ddd62dcfc..8e0eb08949 100644
--- a/src/widgets/effects/qpixmapfilter_p.h
+++ b/src/widgets/effects/qpixmapfilter_p.h
@@ -142,6 +142,7 @@ class Q_WIDGETS_EXPORT QPixmapColorizeFilter : public QPixmapFilter
 
 public:
     QPixmapColorizeFilter(QObject *parent = 0);
+    ~QPixmapColorizeFilter();
 
     void setColor(const QColor& color);
     QColor color() const;
diff --git a/src/widgets/graphicsview/qgraphicsproxywidget.cpp b/src/widgets/graphicsview/qgraphicsproxywidget.cpp
index 3e39f1f418..3ea04efc6b 100644
--- a/src/widgets/graphicsview/qgraphicsproxywidget.cpp
+++ b/src/widgets/graphicsview/qgraphicsproxywidget.cpp
@@ -202,6 +202,13 @@ QGraphicsProxyWidgetPrivate::QGraphicsProxyWidgetPrivate()
 {
 }
 
+/*!
+    \internal
+*/
+QGraphicsProxyWidgetPrivate::~QGraphicsProxyWidgetPrivate()
+{
+}
+
 /*!
     \internal
 */
diff --git a/src/widgets/graphicsview/qgraphicsproxywidget_p.h b/src/widgets/graphicsview/qgraphicsproxywidget_p.h
index 8229374111..30607f22af 100644
--- a/src/widgets/graphicsview/qgraphicsproxywidget_p.h
+++ b/src/widgets/graphicsview/qgraphicsproxywidget_p.h
@@ -57,6 +57,7 @@ class QGraphicsProxyWidgetPrivate : public QGraphicsWidgetPrivate
     Q_DECLARE_PUBLIC(QGraphicsProxyWidget)
 public:
     QGraphicsProxyWidgetPrivate();
+    ~QGraphicsProxyWidgetPrivate();
 
     void init();
     void sendWidgetMouseEvent(QGraphicsSceneMouseEvent *event);