diff --git a/aos/util/trapezoid_profile.py b/aos/util/trapezoid_profile.py
index f956bf0..af85339 100644
--- a/aos/util/trapezoid_profile.py
+++ b/aos/util/trapezoid_profile.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 
 import numpy