diff --git a/144_reflections_of_laser.py b/144_reflections_of_laser.py
index d733724..ccb919f 100644
--- a/144_reflections_of_laser.py
+++ b/144_reflections_of_laser.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 from math import sqrt, pi
 import matplotlib.pyplot as plt