diff --git a/topics/docker/docker-helloworld.sh b/topics/docker/docker-helloworld.sh
index 31c4408..462c4df 100644
--- a/topics/docker/docker-helloworld.sh
+++ b/topics/docker/docker-helloworld.sh
@@ -1,3 +1,5 @@
+#!/bin/bash
+
 console_log () {
   echo ">>> [Docker] $1"
 }