diff --git a/proxyclient/tools/picocom-sec.sh b/proxyclient/tools/picocom-sec.sh
index 4c1f0ebef..053df37fa 100755
--- a/proxyclient/tools/picocom-sec.sh
+++ b/proxyclient/tools/picocom-sec.sh
@@ -1,3 +1,5 @@
+#!/bin/sh
+
 while true; do
     while [ ! -e /dev/m1n1-sec ]; do sleep 1; done
     picocom --omap crlf --imap lfcrlf -b 500000 /dev/m1n1-sec