diff --git a/kapitel10/signalhantering.py b/kapitel10/signalhantering.py
index be9cdb3..1695728 100644
--- a/kapitel10/signalhantering.py
+++ b/kapitel10/signalhantering.py
@@ -1,3 +1,5 @@
+#!/usr/bin/env python3
+
 import signal
 import sys