diff --git a/masque/pattern.py b/masque/pattern.py
index 6d73c4b..12cae7f 100644
--- a/masque/pattern.py
+++ b/masque/pattern.py
@@ -1106,10 +1106,8 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
                 if port.rotation is not None:
                     p1 = offset + port.offset
                     angle = port.rotation
-                    size = 1.0  # Arrow size based on bounds or fixed
-                    dx = size * numpy.cos(angle)
-                    dy = size * numpy.sin(angle)
-                    p2 = p1 + numpy.array([dx, dy])
+                    size = 1.0  # arrow size
+                    p2 = p1 + size * numpy.array([numpy.cos(angle), numpy.sin(angle)])
 
                     axes.annotate(
                         port_name,