diff --git a/Siv3D/src/Siv3D/Polygon/PolygonDetail.cpp b/Siv3D/src/Siv3D/Polygon/PolygonDetail.cpp
index ed0568ce9c..925e32a330 100644
--- a/Siv3D/src/Siv3D/Polygon/PolygonDetail.cpp
+++ b/Siv3D/src/Siv3D/Polygon/PolygonDetail.cpp
@@ -18,8 +18,7 @@ namespace s3d
 {
 	namespace detail
 	{
-		template <class Type>
-		static RectF CalculateBoundingRect(const Vector2D<Type>* const pVertex, const size_t vertexSize)
+		static RectF CalculateBoundingRect(const Vec2* const pVertex, const size_t vertexSize)
 		{
 			assert(pVertex != nullptr);
 			assert(vertexSize != 0);
@@ -209,7 +208,7 @@ namespace s3d
 		m_indices = std::move(indices);
 
 		// [5 of 5]
-		m_boundingRect = detail::CalculateBoundingRect(pOuterVertex, vertexSize);
+		m_boundingRect = detail::CalculateBoundingRect(m_polygon.outer().data(), m_polygon.outer().size());
 	}
 
 	const Array<Vec2>& Polygon::PolygonDetail::outer() const noexcept
@@ -370,7 +369,7 @@ namespace s3d
 			m_holes.back().insert(m_holes.back().end(), hole.begin(), hole.end());
 		}
 
-		m_boundingRect = detail::CalculateBoundingRect(m_vertices.data(), m_vertices.size());
+		m_boundingRect = detail::CalculateBoundingRect(m_polygon.outer().data(), m_polygon.outer().size());
 	}
 
 	void Polygon::PolygonDetail::transform(const double s, const double c, const Vec2& pos)
@@ -417,7 +416,7 @@ namespace s3d
 			m_holes.back().insert(m_holes.back().end(), hole.begin(), hole.end());
 		}
 
-		m_boundingRect = detail::CalculateBoundingRect(m_vertices.data(), m_vertices.size());
+		m_boundingRect = detail::CalculateBoundingRect(m_polygon.outer().data(), m_polygon.outer().size());
 	}
 
 	void Polygon::PolygonDetail::scale(const double s)