diff --git a/python/gui/qgsexpressionbuilderwidget.sip b/python/gui/qgsexpressionbuilderwidget.sip
index acd2598bc3d..5663a7a5bdd 100644
--- a/python/gui/qgsexpressionbuilderwidget.sip
+++ b/python/gui/qgsexpressionbuilderwidget.sip
@@ -79,7 +79,7 @@ class QgsExpressionBuilderWidget : QWidget
 %End
 
   public:
-    QgsExpressionBuilderWidget( QWidget *parent /TransferThis/ );
+    QgsExpressionBuilderWidget( QWidget *parent /TransferThis/ = nullptr );
     ~QgsExpressionBuilderWidget();
 
     /** Sets layer in order to get the fields and values
diff --git a/src/gui/qgsexpressionbuilderwidget.h b/src/gui/qgsexpressionbuilderwidget.h
index f4fbef2b948..09d3a396c5e 100644
--- a/src/gui/qgsexpressionbuilderwidget.h
+++ b/src/gui/qgsexpressionbuilderwidget.h
@@ -118,7 +118,10 @@ class GUI_EXPORT QgsExpressionBuilderWidget : public QWidget, private Ui::QgsExp
 {
     Q_OBJECT
   public:
-    QgsExpressionBuilderWidget( QWidget *parent );
+    /**
+     * Create a new expression builder widget with an optional parent.
+     */
+    QgsExpressionBuilderWidget( QWidget* parent = nullptr );
     ~QgsExpressionBuilderWidget();
 
     /** Sets layer in order to get the fields and values