diff --git a/src/wsdd.py b/src/wsdd.py
index dd29577..a38fb66 100755
--- a/src/wsdd.py
+++ b/src/wsdd.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python3
+#!/usr/bin/python3.9
 
 # Implements a target service according to the Web Service Discovery
 # specification.