diff --git a/Tools/demo/redemo.py b/Tools/demo/redemo.py
old mode 100644
new mode 100755
index 52863324c2d..b10b03021d0
--- a/Tools/demo/redemo.py
+++ b/Tools/demo/redemo.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 """Basic regular expression demostration facility (Perl style syntax)."""
 
 from tkinter import *