--- a/utils/novnc_proxy
+++ b/utils/novnc_proxy
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/sh
 
 # Copyright (C) 2018 The noVNC Authors
 # Licensed under MPL 2.0 or any later version (see LICENSE.txt)
@@ -212,7 +212,7 @@
 ${WEBSOCKIFY} ${SYSLOG_ARG} ${SSLONLY} ${FILEONLY_ARG} --web ${WEB} ${CERT:+--cert ${CERT}} ${KEY:+--key ${KEY}} ${LISTEN} ${VNC_DEST} ${HEARTBEAT_ARG} ${IDLETIMEOUT_ARG} ${RECORD:+--record ${RECORD}} ${TIMEOUT_ARG} ${WEBAUTH_ARG} ${AUTHPLUGIN_ARG} ${AUTHSOURCE_ARG} &
 proxy_pid="$!"
 sleep 1
-if [ -z "$proxy_pid" ] || ! ps -eo pid= | grep -w "$proxy_pid" > /dev/null; then
+if [ -z "$proxy_pid" ] || ! ps -o pid= | grep -qw ${proxy_pid}; then
     proxy_pid=
     echo "Failed to start WebSockets proxy"
     exit 1
