diff --git a/local/bin/sphere.sh b/local/bin/sphere.sh
index b10207a..9a6db45 100755
--- a/local/bin/sphere.sh
+++ b/local/bin/sphere.sh
@@ -1,3 +1,4 @@
+#!/bin/sh
 
 cmd_url=kelder.zeus.ugent.be/webcam/cgi/ptdc.cgi