diff --git a/nhf/touhou/shiki_eiki/crown.py b/nhf/touhou/shiki_eiki/crown.py
index 0d62b4d..bbeb3d5 100644
--- a/nhf/touhou/shiki_eiki/crown.py
+++ b/nhf/touhou/shiki_eiki/crown.py
@@ -443,7 +443,10 @@ class Crown(Model):
         p_top5_c1 = p_top5 * Cq.Location.from2d(0.103 * dx, 0.017 * dy)
         p_top5_c2 = p_top5 * Cq.Location.from2d(0.158 * dx, 0.034 * dy)
         p_base_c = Cq.Location.from2d(1.245 * dx, 0.55 * dy)
-        p_base = Cq.Location.from2d(dx, 0)
+
+        y0 = self.slot_h0 / math.cos(self.slot_theta)
+        phi2 = self.slot_phi / 2
+        p_base = Cq.Location.from2d(y0 * math.sin(phi2), -y0 + y0 * math.cos(phi2))
 
         bezier_groups = [
             [
@@ -485,8 +488,9 @@ class Crown(Model):
         ]
         sketch = (
             Cq.Sketch()
-            .segment(
+            .arc(
                 p_base.to2d_pos(),
+                (0, 0),
                 p_base.flip_x().to2d_pos(),
             )
         )