diff --git a/boxes/drawing.py b/boxes/drawing.py
index d21d73a..a0696a7 100644
--- a/boxes/drawing.py
+++ b/boxes/drawing.py
@@ -265,6 +265,8 @@ class Context:
         self._line_to(x, y)
 
     def _arc(self, xc, yc, radius, angle1, angle2, direction):
+        if abs(angle1 - angle2) < EPS or radius < EPS:
+            return
         x1, y1 = radius * math.cos(angle1) + xc, radius * math.sin(angle1) + yc
         x4, y4 = radius * math.cos(angle2) + xc, radius * math.sin(angle2) + yc