diff --git a/python/gui/auto_generated/symbology/qgs25drendererwidget.sip.in b/python/gui/auto_generated/symbology/qgs25drendererwidget.sip.in
index 2f127f1875a..5e6cbfbe4e9 100644
--- a/python/gui/auto_generated/symbology/qgs25drendererwidget.sip.in
+++ b/python/gui/auto_generated/symbology/qgs25drendererwidget.sip.in
@@ -33,6 +33,7 @@ Constructor
 :param style:
 :param renderer: the mask renderer (will not take ownership)
 %End
+    ~Qgs25DRendererWidget();
 
     virtual QgsFeatureRenderer *renderer();
 
diff --git a/python/gui/auto_generated/symbology/qgsembeddedsymbolrendererwidget.sip.in b/python/gui/auto_generated/symbology/qgsembeddedsymbolrendererwidget.sip.in
index 2877cce0c13..74e36c341a6 100644
--- a/python/gui/auto_generated/symbology/qgsembeddedsymbolrendererwidget.sip.in
+++ b/python/gui/auto_generated/symbology/qgsembeddedsymbolrendererwidget.sip.in
@@ -38,6 +38,7 @@ Constructor
 :param style:
 :param renderer: the merged feature renderer (will not take ownership)
 %End
+    ~QgsEmbeddedSymbolRendererWidget();
 
     virtual QgsFeatureRenderer *renderer();
 
diff --git a/python/gui/auto_generated/symbology/qgsheatmaprendererwidget.sip.in b/python/gui/auto_generated/symbology/qgsheatmaprendererwidget.sip.in
index c6460b7950b..f5a0cf7aa61 100644
--- a/python/gui/auto_generated/symbology/qgsheatmaprendererwidget.sip.in
+++ b/python/gui/auto_generated/symbology/qgsheatmaprendererwidget.sip.in
@@ -33,6 +33,7 @@ Constructor
 :param style:
 :param renderer: the mask renderer (will not take ownership)
 %End
+    ~QgsHeatmapRendererWidget();
 
     virtual QgsFeatureRenderer *renderer();
 
diff --git a/python/gui/auto_generated/symbology/qgsinvertedpolygonrendererwidget.sip.in b/python/gui/auto_generated/symbology/qgsinvertedpolygonrendererwidget.sip.in
index f30f5c52b5d..d6255d2aee9 100644
--- a/python/gui/auto_generated/symbology/qgsinvertedpolygonrendererwidget.sip.in
+++ b/python/gui/auto_generated/symbology/qgsinvertedpolygonrendererwidget.sip.in
@@ -38,6 +38,7 @@ Constructor
 :param style:
 :param renderer: the mask renderer (will not take ownership)
 %End
+    ~QgsInvertedPolygonRendererWidget();
 
     virtual QgsFeatureRenderer *renderer();
 
diff --git a/python/gui/auto_generated/symbology/qgsmergedfeaturerendererwidget.sip.in b/python/gui/auto_generated/symbology/qgsmergedfeaturerendererwidget.sip.in
index 1d79fa66363..25d24cdd26e 100644
--- a/python/gui/auto_generated/symbology/qgsmergedfeaturerendererwidget.sip.in
+++ b/python/gui/auto_generated/symbology/qgsmergedfeaturerendererwidget.sip.in
@@ -38,6 +38,7 @@ Constructor
 :param style:
 :param renderer: the merged feature renderer (will not take ownership)
 %End
+    ~QgsMergedFeatureRendererWidget();
 
     virtual QgsFeatureRenderer *renderer();
 
diff --git a/src/gui/symbology/qgs25drendererwidget.cpp b/src/gui/symbology/qgs25drendererwidget.cpp
index 969e444bb11..171dcf6c9b7 100644
--- a/src/gui/symbology/qgs25drendererwidget.cpp
+++ b/src/gui/symbology/qgs25drendererwidget.cpp
@@ -18,6 +18,7 @@
 #include "qgsvectorlayer.h"
 #include "qgsmaplayerstylemanager.h"
 #include "qgsexpressioncontextutils.h"
+#include "qgssymbol.h"
 
 Qgs25DRendererWidget::Qgs25DRendererWidget( QgsVectorLayer *layer, QgsStyle *style, QgsFeatureRenderer *renderer )
   : QgsRendererWidget( layer, style )
@@ -54,7 +55,7 @@ Qgs25DRendererWidget::Qgs25DRendererWidget( QgsVectorLayer *layer, QgsStyle *sty
 
   if ( renderer )
   {
-    mRenderer = Qgs25DRenderer::convertFromRenderer( renderer );
+    mRenderer.reset( Qgs25DRenderer::convertFromRenderer( renderer ) );
   }
 
   mHeightWidget->setLayer( layer );
@@ -85,9 +86,11 @@ Qgs25DRendererWidget::Qgs25DRendererWidget( QgsVectorLayer *layer, QgsStyle *sty
   connect( mWallExpositionShading, &QAbstractButton::toggled, this, &Qgs25DRendererWidget::updateRenderer );
 }
 
+Qgs25DRendererWidget::~Qgs25DRendererWidget() = default;
+
 QgsFeatureRenderer *Qgs25DRendererWidget::renderer()
 {
-  return mRenderer;
+  return mRenderer.get();
 }
 
 void Qgs25DRendererWidget::updateRenderer()
diff --git a/src/gui/symbology/qgs25drendererwidget.h b/src/gui/symbology/qgs25drendererwidget.h
index 553f4a49e95..a50190ee725 100644
--- a/src/gui/symbology/qgs25drendererwidget.h
+++ b/src/gui/symbology/qgs25drendererwidget.h
@@ -48,6 +48,7 @@ class GUI_EXPORT Qgs25DRendererWidget : public QgsRendererWidget, protected Ui::
      * \param renderer the mask renderer (will not take ownership)
      */
     Qgs25DRendererWidget( QgsVectorLayer *layer, QgsStyle *style, QgsFeatureRenderer *renderer SIP_TRANSFER );
+    ~Qgs25DRendererWidget() override;
 
     QgsFeatureRenderer *renderer() override;
 
@@ -57,7 +58,7 @@ class GUI_EXPORT Qgs25DRendererWidget : public QgsRendererWidget, protected Ui::
   private:
     void apply() override SIP_FORCE;
 
-    Qgs25DRenderer *mRenderer = nullptr;
+    std::unique_ptr< Qgs25DRenderer > mRenderer;
 
     friend class QgsAppScreenShots;
 };
diff --git a/src/gui/symbology/qgsembeddedsymbolrendererwidget.cpp b/src/gui/symbology/qgsembeddedsymbolrendererwidget.cpp
index ff00354f5f3..2f67639b409 100644
--- a/src/gui/symbology/qgsembeddedsymbolrendererwidget.cpp
+++ b/src/gui/symbology/qgsembeddedsymbolrendererwidget.cpp
@@ -79,6 +79,8 @@ QgsEmbeddedSymbolRendererWidget::QgsEmbeddedSymbolRendererWidget( QgsVectorLayer
   } );
 }
 
+QgsEmbeddedSymbolRendererWidget::~QgsEmbeddedSymbolRendererWidget() = default;
+
 QgsFeatureRenderer *QgsEmbeddedSymbolRendererWidget::renderer()
 {
   return mRenderer.get();
diff --git a/src/gui/symbology/qgsembeddedsymbolrendererwidget.h b/src/gui/symbology/qgsembeddedsymbolrendererwidget.h
index 9592108d38d..72348f0ded0 100644
--- a/src/gui/symbology/qgsembeddedsymbolrendererwidget.h
+++ b/src/gui/symbology/qgsembeddedsymbolrendererwidget.h
@@ -17,11 +17,11 @@
 
 #include "ui_qgsembeddedsymbolrendererwidgetbase.h"
 #include "qgis_sip.h"
-#include "qgsembeddedsymbolrenderer.h"
 #include "qgsrendererwidget.h"
 #include "qgis_gui.h"
 
 class QMenu;
+class QgsEmbeddedSymbolRenderer;
 
 /**
  * \ingroup gui
@@ -50,6 +50,7 @@ class GUI_EXPORT QgsEmbeddedSymbolRendererWidget : public QgsRendererWidget, pub
      * \param renderer the merged feature renderer (will not take ownership)
      */
     QgsEmbeddedSymbolRendererWidget( QgsVectorLayer *layer, QgsStyle *style, QgsFeatureRenderer *renderer );
+    ~QgsEmbeddedSymbolRendererWidget() override;
 
     QgsFeatureRenderer *renderer() override;
     void setContext( const QgsSymbolWidgetContext &context ) override;
diff --git a/src/gui/symbology/qgsgraduatedsymbolrendererwidget.cpp b/src/gui/symbology/qgsgraduatedsymbolrendererwidget.cpp
index 418ca512645..835c8b9d4a6 100644
--- a/src/gui/symbology/qgsgraduatedsymbolrendererwidget.cpp
+++ b/src/gui/symbology/qgsgraduatedsymbolrendererwidget.cpp
@@ -464,7 +464,7 @@ QgsGraduatedSymbolRendererWidget::QgsGraduatedSymbolRendererWidget( QgsVectorLay
   // setup user interface
   setupUi( this );
 
-  mSymmetryPointValidator = new QDoubleValidator();
+  mSymmetryPointValidator = new QDoubleValidator( this );
   cboSymmetryPoint->setEditable( true );
   cboSymmetryPoint->setValidator( mSymmetryPointValidator );
 
diff --git a/src/gui/symbology/qgsgraduatedsymbolrendererwidget.h b/src/gui/symbology/qgsgraduatedsymbolrendererwidget.h
index 21cd820775c..1df275f5362 100644
--- a/src/gui/symbology/qgsgraduatedsymbolrendererwidget.h
+++ b/src/gui/symbology/qgsgraduatedsymbolrendererwidget.h
@@ -196,7 +196,7 @@ class GUI_EXPORT QgsGraduatedSymbolRendererWidget : public QgsRendererWidget, pr
 
     QgsRangeList mCopyBuffer;
 
-    QDoubleValidator *mSymmetryPointValidator;
+    QDoubleValidator *mSymmetryPointValidator = nullptr;
 
     std::vector< std::unique_ptr< QgsAbstractProcessingParameterWidgetWrapper >> mParameterWidgetWrappers;
 };
diff --git a/src/gui/symbology/qgsheatmaprendererwidget.cpp b/src/gui/symbology/qgsheatmaprendererwidget.cpp
index 17acb2fb845..c849c688d72 100644
--- a/src/gui/symbology/qgsheatmaprendererwidget.cpp
+++ b/src/gui/symbology/qgsheatmaprendererwidget.cpp
@@ -105,11 +105,11 @@ QgsHeatmapRendererWidget::QgsHeatmapRendererWidget( QgsVectorLayer *layer, QgsSt
 
   if ( renderer )
   {
-    mRenderer = QgsHeatmapRenderer::convertFromRenderer( renderer );
+    mRenderer.reset( QgsHeatmapRenderer::convertFromRenderer( renderer ) );
   }
   if ( !mRenderer )
   {
-    mRenderer = new QgsHeatmapRenderer();
+    mRenderer = std::make_unique< QgsHeatmapRenderer >();
   }
 
   btnColorRamp->setShowGradientOnly( true );
@@ -141,9 +141,11 @@ QgsHeatmapRendererWidget::QgsHeatmapRendererWidget( QgsVectorLayer *layer, QgsSt
   connect( mWeightExpressionWidget, static_cast < void ( QgsFieldExpressionWidget::* )( const QString & ) >( &QgsFieldExpressionWidget::fieldChanged ), this, &QgsHeatmapRendererWidget::weightExpressionChanged );
 }
 
+QgsHeatmapRendererWidget::~QgsHeatmapRendererWidget() = default;
+
 QgsFeatureRenderer *QgsHeatmapRendererWidget::renderer()
 {
-  return mRenderer;
+  return mRenderer.get();
 }
 
 void QgsHeatmapRendererWidget::setContext( const QgsSymbolWidgetContext &context )
diff --git a/src/gui/symbology/qgsheatmaprendererwidget.h b/src/gui/symbology/qgsheatmaprendererwidget.h
index 519572d9878..1f068101209 100644
--- a/src/gui/symbology/qgsheatmaprendererwidget.h
+++ b/src/gui/symbology/qgsheatmaprendererwidget.h
@@ -48,12 +48,13 @@ class GUI_EXPORT QgsHeatmapRendererWidget : public QgsRendererWidget, private Ui
      * \param renderer the mask renderer (will not take ownership)
      */
     QgsHeatmapRendererWidget( QgsVectorLayer *layer, QgsStyle *style, QgsFeatureRenderer *renderer );
+    ~QgsHeatmapRendererWidget() override;
 
     QgsFeatureRenderer *renderer() override;
     void setContext( const QgsSymbolWidgetContext &context ) override;
 
   private:
-    QgsHeatmapRenderer *mRenderer = nullptr;
+    std::unique_ptr< QgsHeatmapRenderer > mRenderer;
 
     QgsExpressionContext createExpressionContext() const override;
 
diff --git a/src/gui/symbology/qgsinvertedpolygonrendererwidget.cpp b/src/gui/symbology/qgsinvertedpolygonrendererwidget.cpp
index 76ecc24bbc1..d1f681c19f5 100644
--- a/src/gui/symbology/qgsinvertedpolygonrendererwidget.cpp
+++ b/src/gui/symbology/qgsinvertedpolygonrendererwidget.cpp
@@ -100,6 +100,8 @@ QgsInvertedPolygonRendererWidget::QgsInvertedPolygonRendererWidget( QgsVectorLay
   }
 }
 
+QgsInvertedPolygonRendererWidget::~QgsInvertedPolygonRendererWidget() = default;
+
 QgsFeatureRenderer *QgsInvertedPolygonRendererWidget::renderer()
 {
   if ( mRenderer && mEmbeddedRendererWidget )
diff --git a/src/gui/symbology/qgsinvertedpolygonrendererwidget.h b/src/gui/symbology/qgsinvertedpolygonrendererwidget.h
index 0e71b6058f3..41abc1dbc02 100644
--- a/src/gui/symbology/qgsinvertedpolygonrendererwidget.h
+++ b/src/gui/symbology/qgsinvertedpolygonrendererwidget.h
@@ -17,11 +17,11 @@
 
 #include "ui_qgsinvertedpolygonrendererwidgetbase.h"
 #include "qgis_sip.h"
-#include "qgsinvertedpolygonrenderer.h"
 #include "qgsrendererwidget.h"
 #include "qgis_gui.h"
 
 class QMenu;
+class QgsInvertedPolygonRenderer;
 
 /**
  * \ingroup gui
@@ -50,6 +50,7 @@ class GUI_EXPORT QgsInvertedPolygonRendererWidget : public QgsRendererWidget, pr
      * \param renderer the mask renderer (will not take ownership)
      */
     QgsInvertedPolygonRendererWidget( QgsVectorLayer *layer, QgsStyle *style, QgsFeatureRenderer *renderer );
+    ~QgsInvertedPolygonRendererWidget() override;
 
     QgsFeatureRenderer *renderer() override;
 
diff --git a/src/gui/symbology/qgsmergedfeaturerendererwidget.cpp b/src/gui/symbology/qgsmergedfeaturerendererwidget.cpp
index 043da091d5b..5a3cb4f8d59 100644
--- a/src/gui/symbology/qgsmergedfeaturerendererwidget.cpp
+++ b/src/gui/symbology/qgsmergedfeaturerendererwidget.cpp
@@ -97,6 +97,8 @@ QgsMergedFeatureRendererWidget::QgsMergedFeatureRendererWidget( QgsVectorLayer *
   }
 }
 
+QgsMergedFeatureRendererWidget::~QgsMergedFeatureRendererWidget() = default;
+
 QgsFeatureRenderer *QgsMergedFeatureRendererWidget::renderer()
 {
   if ( mRenderer && mEmbeddedRendererWidget )
diff --git a/src/gui/symbology/qgsmergedfeaturerendererwidget.h b/src/gui/symbology/qgsmergedfeaturerendererwidget.h
index a79c4013999..b14abb2a34d 100644
--- a/src/gui/symbology/qgsmergedfeaturerendererwidget.h
+++ b/src/gui/symbology/qgsmergedfeaturerendererwidget.h
@@ -17,11 +17,11 @@
 
 #include "ui_qgsmergedfeaturerendererwidgetbase.h"
 #include "qgis_sip.h"
-#include "qgsmergedfeaturerenderer.h"
 #include "qgsrendererwidget.h"
 #include "qgis_gui.h"
 
 class QMenu;
+class QgsMergedFeatureRenderer;
 
 /**
  * \ingroup gui
@@ -50,6 +50,7 @@ class GUI_EXPORT QgsMergedFeatureRendererWidget : public QgsRendererWidget, priv
      * \param renderer the merged feature renderer (will not take ownership)
      */
     QgsMergedFeatureRendererWidget( QgsVectorLayer *layer, QgsStyle *style, QgsFeatureRenderer *renderer );
+    ~QgsMergedFeatureRendererWidget() override;
 
     QgsFeatureRenderer *renderer() override;
     void setContext( const QgsSymbolWidgetContext &context ) override;
diff --git a/src/gui/symbology/qgsnullsymbolrendererwidget.cpp b/src/gui/symbology/qgsnullsymbolrendererwidget.cpp
index 494df613a03..d9ca3aa4bab 100644
--- a/src/gui/symbology/qgsnullsymbolrendererwidget.cpp
+++ b/src/gui/symbology/qgsnullsymbolrendererwidget.cpp
@@ -26,15 +26,14 @@ QgsRendererWidget *QgsNullSymbolRendererWidget::create( QgsVectorLayer *layer, Q
 
 QgsNullSymbolRendererWidget::QgsNullSymbolRendererWidget( QgsVectorLayer *layer, QgsStyle *style, QgsFeatureRenderer *renderer )
   : QgsRendererWidget( layer, style )
-
 {
   if ( renderer )
   {
-    mRenderer = QgsNullSymbolRenderer::convertFromRenderer( renderer );
+    mRenderer.reset( QgsNullSymbolRenderer::convertFromRenderer( renderer ) );
   }
   if ( !mRenderer )
   {
-    mRenderer = new QgsNullSymbolRenderer();
+    mRenderer = std::make_unique< QgsNullSymbolRenderer >();
   }
 
   QGridLayout *layout = new QGridLayout( this );
@@ -42,12 +41,9 @@ QgsNullSymbolRendererWidget::QgsNullSymbolRendererWidget( QgsVectorLayer *layer,
   layout->addWidget( label );
 }
 
-QgsNullSymbolRendererWidget::~QgsNullSymbolRendererWidget()
-{
-  delete mRenderer;
-}
+QgsNullSymbolRendererWidget::~QgsNullSymbolRendererWidget() = default;
 
 QgsFeatureRenderer *QgsNullSymbolRendererWidget::renderer()
 {
-  return mRenderer;
+  return mRenderer.get();
 }
diff --git a/src/gui/symbology/qgsnullsymbolrendererwidget.h b/src/gui/symbology/qgsnullsymbolrendererwidget.h
index d23e7f2052d..806151e449b 100644
--- a/src/gui/symbology/qgsnullsymbolrendererwidget.h
+++ b/src/gui/symbology/qgsnullsymbolrendererwidget.h
@@ -49,7 +49,7 @@ class GUI_EXPORT QgsNullSymbolRendererWidget : public QgsRendererWidget
   protected:
 
     //! Renderer being configured by the widget
-    QgsNullSymbolRenderer *mRenderer = nullptr;
+    std::unique_ptr< QgsNullSymbolRenderer > mRenderer;
 
 };
 
diff --git a/src/gui/symbology/qgspointclusterrendererwidget.cpp b/src/gui/symbology/qgspointclusterrendererwidget.cpp
index b84f033da76..d747f993dad 100644
--- a/src/gui/symbology/qgspointclusterrendererwidget.cpp
+++ b/src/gui/symbology/qgspointclusterrendererwidget.cpp
@@ -63,11 +63,11 @@ QgsPointClusterRendererWidget::QgsPointClusterRendererWidget( QgsVectorLayer *la
 
   if ( renderer )
   {
-    mRenderer = QgsPointClusterRenderer::convertFromRenderer( renderer );
+    mRenderer.reset( QgsPointClusterRenderer::convertFromRenderer( renderer ) );
   }
   if ( !mRenderer )
   {
-    mRenderer = new QgsPointClusterRenderer();
+    mRenderer = std::make_unique< QgsPointClusterRenderer >();
   }
 
   blockAllSignals( true );
@@ -109,14 +109,11 @@ QgsPointClusterRendererWidget::QgsPointClusterRendererWidget( QgsVectorLayer *la
   mCenterSymbolToolButton->registerExpressionContextGenerator( this );
 }
 
-QgsPointClusterRendererWidget::~QgsPointClusterRendererWidget()
-{
-  delete mRenderer;
-}
+QgsPointClusterRendererWidget::~QgsPointClusterRendererWidget() = default;
 
 QgsFeatureRenderer *QgsPointClusterRendererWidget::renderer()
 {
-  return mRenderer;
+  return mRenderer.get();
 }
 
 void QgsPointClusterRendererWidget::setContext( const QgsSymbolWidgetContext &context )
diff --git a/src/gui/symbology/qgspointclusterrendererwidget.h b/src/gui/symbology/qgspointclusterrendererwidget.h
index 5cc01387b82..7660ce196b1 100644
--- a/src/gui/symbology/qgspointclusterrendererwidget.h
+++ b/src/gui/symbology/qgspointclusterrendererwidget.h
@@ -64,7 +64,7 @@ class GUI_EXPORT QgsPointClusterRendererWidget: public QgsRendererWidget, public
     QgsExpressionContext createExpressionContext() const override;
 
   private:
-    QgsPointClusterRenderer *mRenderer = nullptr;
+    std::unique_ptr< QgsPointClusterRenderer > mRenderer;
 
     void blockAllSignals( bool block );
     void setupBlankUi( const QString &layerName );
diff --git a/src/gui/symbology/qgspointdisplacementrendererwidget.cpp b/src/gui/symbology/qgspointdisplacementrendererwidget.cpp
index 44f5375a736..d8e62b414fa 100644
--- a/src/gui/symbology/qgspointdisplacementrendererwidget.cpp
+++ b/src/gui/symbology/qgspointdisplacementrendererwidget.cpp
@@ -71,11 +71,11 @@ QgsPointDisplacementRendererWidget::QgsPointDisplacementRendererWidget( QgsVecto
 
   if ( renderer )
   {
-    mRenderer = QgsPointDisplacementRenderer::convertFromRenderer( renderer );
+    mRenderer.reset( QgsPointDisplacementRenderer::convertFromRenderer( renderer ) );
   }
   if ( !mRenderer )
   {
-    mRenderer = new QgsPointDisplacementRenderer();
+    mRenderer = std::make_unique< QgsPointDisplacementRenderer >();
   }
 
   blockAllSignals( true );
@@ -176,14 +176,11 @@ QgsPointDisplacementRendererWidget::QgsPointDisplacementRendererWidget( QgsVecto
   mCenterSymbolToolButton->registerExpressionContextGenerator( this );
 }
 
-QgsPointDisplacementRendererWidget::~QgsPointDisplacementRendererWidget()
-{
-  delete mRenderer;
-}
+QgsPointDisplacementRendererWidget::~QgsPointDisplacementRendererWidget() = default;
 
 QgsFeatureRenderer *QgsPointDisplacementRendererWidget::renderer()
 {
-  return mRenderer;
+  return mRenderer.get();
 }
 
 void QgsPointDisplacementRendererWidget::setContext( const QgsSymbolWidgetContext &context )
diff --git a/src/gui/symbology/qgspointdisplacementrendererwidget.h b/src/gui/symbology/qgspointdisplacementrendererwidget.h
index d4d15270e70..60436aebfa5 100644
--- a/src/gui/symbology/qgspointdisplacementrendererwidget.h
+++ b/src/gui/symbology/qgspointdisplacementrendererwidget.h
@@ -44,7 +44,7 @@ class GUI_EXPORT QgsPointDisplacementRendererWidget: public QgsRendererWidget, p
     QgsExpressionContext createExpressionContext() const override;
 
   private:
-    QgsPointDisplacementRenderer *mRenderer = nullptr;
+    std::unique_ptr< QgsPointDisplacementRenderer > mRenderer;
 
     void blockAllSignals( bool block );
     void setupBlankUi( const QString &layerName );
diff --git a/src/gui/symbology/qgsrulebasedrendererwidget.cpp b/src/gui/symbology/qgsrulebasedrendererwidget.cpp
index 0d340a0616d..9d4d4eef354 100644
--- a/src/gui/symbology/qgsrulebasedrendererwidget.cpp
+++ b/src/gui/symbology/qgsrulebasedrendererwidget.cpp
@@ -61,20 +61,20 @@ QgsRuleBasedRendererWidget::QgsRuleBasedRendererWidget( QgsVectorLayer *layer, Q
 
   if ( renderer )
   {
-    mRenderer = QgsRuleBasedRenderer::convertFromRenderer( renderer, layer );
+    mRenderer.reset( QgsRuleBasedRenderer::convertFromRenderer( renderer, layer ) );
   }
   if ( !mRenderer )
   {
     // some default options
     QgsSymbol *symbol = QgsSymbol::defaultSymbol( mLayer->geometryType() );
 
-    mRenderer = new QgsRuleBasedRenderer( symbol );
+    mRenderer = std::make_unique< QgsRuleBasedRenderer >( symbol );
   }
 
   setupUi( this );
   this->layout()->setContentsMargins( 0, 0, 0, 0 );
 
-  mModel = new QgsRuleBasedRendererModel( mRenderer, viewRules );
+  mModel = new QgsRuleBasedRendererModel( mRenderer.get(), viewRules );
 #ifdef ENABLE_MODELTEST
   new ModelTest( mModel, this ); // for model validity checking
 #endif
@@ -135,12 +135,11 @@ QgsRuleBasedRendererWidget::QgsRuleBasedRendererWidget( QgsVectorLayer *layer, Q
 QgsRuleBasedRendererWidget::~QgsRuleBasedRendererWidget()
 {
   qDeleteAll( mCopyBuffer );
-  delete mRenderer;
 }
 
 QgsFeatureRenderer *QgsRuleBasedRendererWidget::renderer()
 {
-  return mRenderer;
+  return mRenderer.get();
 }
 
 void QgsRuleBasedRendererWidget::setDockMode( bool dockMode )
@@ -452,7 +451,7 @@ void QgsRuleBasedRendererWidget::setRenderingOrder()
   QgsPanelWidget *panel = QgsPanelWidget::findParentPanel( this );
   if ( panel && panel->dockMode() )
   {
-    QgsSymbolLevelsWidget *widget = new QgsSymbolLevelsWidget( mRenderer, true, panel );
+    QgsSymbolLevelsWidget *widget = new QgsSymbolLevelsWidget( mRenderer.get(), true, panel );
     widget->setForceOrderingEnabled( true );
     widget->setPanelTitle( tr( "Symbol Levels" ) );
     connect( widget, &QgsPanelWidget::widgetChanged, this, [ = ]()
@@ -463,7 +462,7 @@ void QgsRuleBasedRendererWidget::setRenderingOrder()
   }
   else
   {
-    QgsSymbolLevelsDialog dlg( mRenderer, true, panel );
+    QgsSymbolLevelsDialog dlg( mRenderer.get(), true, panel );
     dlg.setForceOrderingEnabled( true );
     if ( dlg.exec() )
     {
diff --git a/src/gui/symbology/qgsrulebasedrendererwidget.h b/src/gui/symbology/qgsrulebasedrendererwidget.h
index 937b971af0f..18713bf7bed 100644
--- a/src/gui/symbology/qgsrulebasedrendererwidget.h
+++ b/src/gui/symbology/qgsrulebasedrendererwidget.h
@@ -166,7 +166,7 @@ class GUI_EXPORT QgsRuleBasedRendererWidget : public QgsRendererWidget, private
     void refreshSymbolView() override;
     void keyPressEvent( QKeyEvent *event ) override;
 
-    QgsRuleBasedRenderer *mRenderer = nullptr;
+    std::unique_ptr< QgsRuleBasedRenderer > mRenderer;
     QgsRuleBasedRendererModel *mModel = nullptr;
 
     QMenu *mRefineMenu = nullptr;