diff --git a/pcbnew/board_items_to_polygon_shape_transform.cpp b/pcbnew/board_items_to_polygon_shape_transform.cpp
index f0625cb1d3..af13f39964 100644
--- a/pcbnew/board_items_to_polygon_shape_transform.cpp
+++ b/pcbnew/board_items_to_polygon_shape_transform.cpp
@@ -488,7 +488,7 @@ void PCB_SHAPE::TransformShapeWithClearanceToPolygon( SHAPE_POLY_SET& aCornerBuf
 
         // Build the polygon with the actual position and orientation:
         std::vector<wxPoint> poly;
-        poly = BuildPolyPointsList();
+        DupPolyPointsList( poly );
 
         for( wxPoint& point : poly )
         {
diff --git a/pcbnew/pcb_shape.cpp b/pcbnew/pcb_shape.cpp
index f9461cd942..bad23b12cb 100644
--- a/pcbnew/pcb_shape.cpp
+++ b/pcbnew/pcb_shape.cpp
@@ -1274,20 +1274,20 @@ std::shared_ptr<SHAPE> PCB_SHAPE::GetEffectiveShape( PCB_LAYER_ID aLayer ) const
 }
 
 
-const std::vector<wxPoint> PCB_SHAPE::BuildPolyPointsList() const
+void PCB_SHAPE::DupPolyPointsList( std::vector<wxPoint>& aBuffer ) const
 {
-    std::vector<wxPoint> rv;
-
     if( m_poly.OutlineCount() )
     {
-        if( m_poly.COutline( 0 ).PointCount() )
+        int pointCount = m_poly.COutline( 0 ).PointCount();
+
+        if( pointCount )
         {
+            aBuffer.reserve( pointCount );
+
             for ( auto iter = m_poly.CIterate(); iter; iter++ )
-                rv.emplace_back( iter->x, iter->y );
+                aBuffer.emplace_back( iter->x, iter->y );
         }
     }
-
-    return rv;
 }
 
 
diff --git a/pcbnew/pcb_shape.h b/pcbnew/pcb_shape.h
index a10288eaab..c1139f0947 100644
--- a/pcbnew/pcb_shape.h
+++ b/pcbnew/pcb_shape.h
@@ -223,13 +223,13 @@ public:
     const std::vector<wxPoint>& GetBezierPoints() const { return m_bezierPoints; }
 
     /**
-     * Build and return the list of corners in a std::vector<wxPoint>
+     * Duplicate the list of corners in a std::vector<wxPoint>
      *
      * It must be used only to convert the SHAPE_POLY_SET internal corner buffer
      * to a list of wxPoints, and nothing else, because it duplicates the buffer,
      * that is inefficient to know for instance the corner count
      */
-    const std::vector<wxPoint> BuildPolyPointsList() const;
+    void DupPolyPointsList( std::vector<wxPoint>& aBuffer ) const;
 
     /**
      * @return the number of corners of the polygonal shape
diff --git a/pcbnew/plot_brditems_plotter.cpp b/pcbnew/plot_brditems_plotter.cpp
index e4a8129792..210d5a0c8c 100644
--- a/pcbnew/plot_brditems_plotter.cpp
+++ b/pcbnew/plot_brditems_plotter.cpp
@@ -627,25 +627,20 @@ void BRDITEMS_PLOTTER::PlotFootprintGraphicItem( const FP_SHAPE* aShape )
     case SHAPE_T::POLY:
         if( aShape->IsPolyShapeValid() )
         {
-            const std::vector<wxPoint> &polyPoints = aShape->BuildPolyPointsList();
+            std::vector<wxPoint> cornerList;
+            aShape->DupPolyPointsList( cornerList );
 
             // We must compute board coordinates from m_PolyList which are relative to the parent
             // position at orientation 0
             const FOOTPRINT *parentFootprint = aShape->GetParentFootprint();
 
-            std::vector<wxPoint> cornerList;
-
-            cornerList.reserve( polyPoints.size() );
-
-            for( wxPoint corner : polyPoints )
+            if( parentFootprint )
             {
-                if( parentFootprint )
+                for( wxPoint corner : cornerList )
                 {
                     RotatePoint( &corner, parentFootprint->GetOrientation() );
                     corner += parentFootprint->GetPosition();
                 }
-
-                cornerList.push_back( corner );
             }
 
             if( sketch || thickness > 0 )
diff --git a/pcbnew/tools/pcb_grid_helper.cpp b/pcbnew/tools/pcb_grid_helper.cpp
index 640cb72a31..d2456045f0 100644
--- a/pcbnew/tools/pcb_grid_helper.cpp
+++ b/pcbnew/tools/pcb_grid_helper.cpp
@@ -579,8 +579,10 @@ void PCB_GRID_HELPER::computeAnchors( BOARD_ITEM* aItem, const VECTOR2I& aRefPos
                 {
                     SHAPE_LINE_CHAIN lc;
                     lc.SetClosed( true );
+                    std::vector<wxPoint> poly;
+                    shape->DupPolyPointsList( poly );
 
-                    for( const wxPoint& p : shape->BuildPolyPointsList() )
+                    for( const wxPoint& p : poly )
                     {
                         addAnchor( p, CORNER | SNAPPABLE, shape );
                         lc.Append( p );
diff --git a/pcbnew/tools/pcb_point_editor.cpp b/pcbnew/tools/pcb_point_editor.cpp
index a3581123b6..f31d5b9ff0 100644
--- a/pcbnew/tools/pcb_point_editor.cpp
+++ b/pcbnew/tools/pcb_point_editor.cpp
@@ -1596,7 +1596,8 @@ void PCB_POINT_EDITOR::updatePoints()
 
         case SHAPE_T::POLY:
         {
-            const auto& points = shape->BuildPolyPointsList();
+            std::vector<wxPoint> points;
+            shape->DupPolyPointsList( points );
 
             if( m_editPoints->PointsSize() != (unsigned) points.size() )
             {