diff --git a/src/gui/qgspropertyassistantwidget.cpp b/src/gui/qgspropertyassistantwidget.cpp
index b5d747e85ae0..fb1ebdacf7eb 100644
--- a/src/gui/qgspropertyassistantwidget.cpp
+++ b/src/gui/qgspropertyassistantwidget.cpp
@@ -135,6 +135,7 @@ QgsPropertyAssistantWidget::QgsPropertyAssistantWidget( QWidget *parent,
   connect( minValueSpinBox, static_cast < void ( QgsDoubleSpinBox::* )( double ) > ( &QgsDoubleSpinBox::valueChanged ), this, &QgsPropertyAssistantWidget::widgetChanged );
   connect( maxValueSpinBox, static_cast < void ( QgsDoubleSpinBox::* )( double ) > ( &QgsDoubleSpinBox::valueChanged ), this, &QgsPropertyAssistantWidget::widgetChanged );
   connect( mExpressionWidget, static_cast < void ( QgsFieldExpressionWidget::* )( const QString & ) > ( &QgsFieldExpressionWidget::fieldChanged ), this, &QgsPropertyAssistantWidget::widgetChanged );
+  connect( mTransformCurveCheckBox, &QgsCollapsibleGroupBox::toggled, this, &QgsPropertyAssistantWidget::widgetChanged );
   connect( mCurveEditor, &QgsCurveEditorWidget::changed, this, &QgsPropertyAssistantWidget::widgetChanged );
   connect( this, &QgsPropertyAssistantWidget::widgetChanged, this, &QgsPropertyAssistantWidget::updatePreview );
   updatePreview();
diff --git a/src/gui/qgspropertyassistantwidget.h b/src/gui/qgspropertyassistantwidget.h
index a66c6b1ef7f9..d5fdd7b17be9 100644
--- a/src/gui/qgspropertyassistantwidget.h
+++ b/src/gui/qgspropertyassistantwidget.h
@@ -154,7 +154,6 @@ class GUI_EXPORT QgsPropertyAssistantWidget : public QgsPanelWidget, private Ui:
     void computeValuesFromLayer();
     void updatePreview();
 
-
   private:
 
     QgsPropertyDefinition mDefinition;
@@ -170,7 +169,6 @@ class GUI_EXPORT QgsPropertyAssistantWidget : public QgsPanelWidget, private Ui:
 
     bool computeValuesFromExpression( const QString &expression, double &minValue, double &maxValue ) const;
     bool computeValuesFromField( const QString &fieldName, double &minValue, double &maxValue ) const;
-
 };
 
 #ifndef SIP_RUN