diff --git a/experimental/Pomdog.Experimental/UI/StackPanel.cpp b/experimental/Pomdog.Experimental/UI/StackPanel.cpp
index a2445534c..36cd39332 100644
--- a/experimental/Pomdog.Experimental/UI/StackPanel.cpp
+++ b/experimental/Pomdog.Experimental/UI/StackPanel.cpp
@@ -102,7 +102,7 @@ void StackPanel::OnPointerMoved(const PointerPoint& pointerPoint)
 
         ///@note recalculate position in current coordinate system
         pointInView = UIHelper::ConvertToChildSpace(pointerPoint.Position, GetGlobalTransform());
-        position = Vector2(pointInView.X, pointInView.Y);
+        position = MathHelper::ToVector2(pointInView);
         startTouchPoint = position;
     }
 }
diff --git a/experimental/Pomdog.Experimental/UI/UIHelper.hpp b/experimental/Pomdog.Experimental/UI/UIHelper.hpp
index 4c3ff10d2..bbe5942f2 100644
--- a/experimental/Pomdog.Experimental/UI/UIHelper.hpp
+++ b/experimental/Pomdog.Experimental/UI/UIHelper.hpp
@@ -2,6 +2,7 @@
 
 #pragma once
 
+#include "Pomdog/Math/MathHelper.hpp"
 #include "Pomdog/Math/Point2D.hpp"
 #include "Pomdog/Math/Vector2.hpp"
 #include "Pomdog/Math/Matrix3x2.hpp"
@@ -19,8 +20,8 @@ struct UIHelper {
     static Point2D ConvertToChildSpace(
         const Point2D& position, const Matrix3x2& transform)
     {
-        auto positionInChild = ConvertToChildSpace(Vector2(position.X, position.Y), transform);
-        return Point2D(positionInChild.X, positionInChild.Y);
+        auto positionInChild = ConvertToChildSpace(MathHelper::ToVector2(position), transform);
+        return MathHelper::ToPoint2D(positionInChild);
     }
 };