diff --git a/update_subtrees.sh b/update_subtrees.sh
old mode 100644
new mode 100755
index 68a5be0..6e0537d
--- a/update_subtrees.sh
+++ b/update_subtrees.sh
@@ -1 +1,2 @@
+#!/bin/bash
 git subtree pull --prefix subtrees/columbus git@dominik-roth.eu:dodox/Columbus.git master --squash