diff --git a/04-code-golf/tf-04-pn.py b/04-code-golf/tf-04-pn.py
index 87c6b3e..3071f64 100755
--- a/04-code-golf/tf-04-pn.py
+++ b/04-code-golf/tf-04-pn.py
@@ -1,3 +1,4 @@
+#!/usr/bin/env python
 # My golf score is slightly lower!  
 # Best wishes, Peter Norvig