diff --git a/Sources/BigRing.swift b/Sources/BigRing.swift
index 8da6369..397efc8 100644
--- a/Sources/BigRing.swift
+++ b/Sources/BigRing.swift
@@ -19,6 +19,9 @@ struct BigRing: View {
     
     var bigRingDiameter: CGFloat
     
+    // 円周率を直接記述する
+    private let piValue: Double = 3.14159265358979
+    
     var body: some View {
         ZStack {
             Circle().stroke(bigRingStrokeColor, lineWidth: 10)
@@ -31,12 +34,12 @@ struct BigRing: View {
                 let radius = min(bigRingDiameter, bigRingDiameter) / 2
                 let center = CGPoint(x: bigRingDiameter / 2, y: bigRingDiameter / 2)
                 
-                let additionalAngle = Double.pi / 8 // 線の開始位置を調整
+                let additionalAngle = piValue / 8 // 線の開始位置を調整
              
                 ForEach(0..<8) { i in
                     Path { path in
                         path.move(to: center)
-                        let angle = CGFloat(i) * .pi / 4 + additionalAngle
+                        let angle = CGFloat(i) * piValue / 4 + additionalAngle
                         let endX = center.x + radius * cos(angle)
                         let endY = center.y + radius * sin(angle)
                         path.addLine(to: CGPoint(x: endX, y: endY))
diff --git a/Sources/CGPoint+Joystick.swift b/Sources/CGPoint+Joystick.swift
index 5a62de9..c20ae27 100644
--- a/Sources/CGPoint+Joystick.swift
+++ b/Sources/CGPoint+Joystick.swift
@@ -20,12 +20,15 @@ extension CGPoint {
     /// Get radian from point on circle
     func getRadian(pointOnCircle: CGPoint) -> CGFloat {
         
+        // 円周率を直接記述する
+        let piValue: Double = 3.14159265358979
+        
         let originX = pointOnCircle.x - self.x
         let originY = pointOnCircle.y - self.y
         var radian = atan2(originY, originX)
         
         while radian < 0 {
-            radian += CGFloat(2 * Double.pi)
+            radian += CGFloat(2 * piValue)
         }
         
         return radian