diff --git a/pcbnew/pcb_expr_functions.cpp b/pcbnew/pcb_expr_functions.cpp
index deb2cea0a2..acb695bca8 100644
--- a/pcbnew/pcb_expr_functions.cpp
+++ b/pcbnew/pcb_expr_functions.cpp
@@ -413,6 +413,7 @@ bool collidesWithArea( BOARD_ITEM* aItem, PCB_EXPR_CONTEXT* aCtx, ZONE* aArea )
     // This is particularly important for detecting copper fills as they will be exactly
     // touching along the entire exclusion border.
     SHAPE_POLY_SET areaOutline = aArea->Outline()->CloneDropTriangulation();
+    areaOutline.ClearArcs();
     areaOutline.Deflate( board->GetDesignSettings().GetDRCEpsilon(),
                          SHAPE_POLY_SET::ALLOW_ACUTE_CORNERS, ARC_LOW_DEF );