diff --git a/lib/xmet/hodograph.py b/lib/xmet/hodograph.py
index 731e863..4186006 100644
--- a/lib/xmet/hodograph.py
+++ b/lib/xmet/hodograph.py
@@ -72,7 +72,7 @@ class Hodograph():
 
             cr.arc(x + cx,
                    x + cy,
-                   sy - self.radius,
+                   abs(sy - cy),
                    0,
                    2*math.pi)