diff --git a/pcbnew/board_items_to_polygon_shape_transform.cpp b/pcbnew/board_items_to_polygon_shape_transform.cpp
index 2207abfb32..6fd68988d5 100644
--- a/pcbnew/board_items_to_polygon_shape_transform.cpp
+++ b/pcbnew/board_items_to_polygon_shape_transform.cpp
@@ -1,8 +1,8 @@
 /*
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
- * Copyright (C) 2009-2018 Jean-Pierre Charras, jp.charras at wanadoo.fr
- * Copyright (C) 1992-2019 KiCad Developers, see AUTHORS.txt for contributors.
+ * Copyright (C) 2009-2021 Jean-Pierre Charras, jp.charras at wanadoo.fr
+ * Copyright (C) 1992-2021 KiCad Developers, see AUTHORS.txt for contributors.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -731,7 +731,7 @@ void PAD::TransformShapeWithClearanceToPolygon( SHAPE_POLY_SET& aCornerBuffer,
     case PAD_SHAPE_CUSTOM:
     {
         SHAPE_POLY_SET outline;
-        MergePrimitivesAsPolygon( &outline, aLayer );
+        MergePrimitivesAsPolygon( &outline, aLayer, aErrorLoc );
         outline.Rotate( -DECIDEG2RAD( m_orient ) );
         outline.Move( VECTOR2I( m_pos ) );
 
diff --git a/pcbnew/pad.h b/pcbnew/pad.h
index ee79b7d9e5..b74167ee6b 100644
--- a/pcbnew/pad.h
+++ b/pcbnew/pad.h
@@ -279,8 +279,16 @@ public:
      * Merge all basic shapes to a #SHAPE_POLY_SET.
      *
      * @note The results are relative to the pad position, orientation 0.
+     *
+     * @param aMergedPolygon will store the final polygon
+     * @param aLayer is the layer to take in account, as the exact shape can depend on the layer
+     * @param aErrorLoc is used when a circle (or arc) is approximated by segments
+     *  = ERROR_INSIDE to build a polygon inside the arc/circle (usual shape to raw/plot)
+     *  = ERROR_OUIDE to build a polygon outside the arc/circle
+     * (for instance when building a clearance area)
      */
-    void MergePrimitivesAsPolygon( SHAPE_POLY_SET* aMergedPolygon, PCB_LAYER_ID aLayer ) const;
+    void MergePrimitivesAsPolygon( SHAPE_POLY_SET* aMergedPolygon, PCB_LAYER_ID aLayer,
+                                   ERROR_LOC aErrorLoc = ERROR_INSIDE ) const;
 
     /**
      * Clear the basic shapes list.
diff --git a/pcbnew/pad_custom_shape_functions.cpp b/pcbnew/pad_custom_shape_functions.cpp
index 6747f5bbc1..eb7f8a71a6 100644
--- a/pcbnew/pad_custom_shape_functions.cpp
+++ b/pcbnew/pad_custom_shape_functions.cpp
@@ -200,7 +200,8 @@ void PAD::addPadPrimitivesToPolygon( SHAPE_POLY_SET* aMergedPolygon, PCB_LAYER_I
     }
 }
 
-void PAD::MergePrimitivesAsPolygon( SHAPE_POLY_SET* aMergedPolygon, PCB_LAYER_ID aLayer ) const
+void PAD::MergePrimitivesAsPolygon( SHAPE_POLY_SET* aMergedPolygon, PCB_LAYER_ID aLayer,
+                                    ERROR_LOC aErrorLoc ) const
 {
     BOARD* board = GetBoard();
     int    maxError = board ? board->GetDesignSettings().m_MaxError: ARC_HIGH_DEF;
@@ -225,7 +226,7 @@ void PAD::MergePrimitivesAsPolygon( SHAPE_POLY_SET* aMergedPolygon, PCB_LAYER_ID
         break;
     }
 
-    addPadPrimitivesToPolygon( aMergedPolygon, aLayer, maxError, ERROR_INSIDE );
+    addPadPrimitivesToPolygon( aMergedPolygon, aLayer, maxError, aErrorLoc );
 }