diff --git a/install.sh b/install.sh
index 9a0abe1..1a09b66 100755
--- a/install.sh
+++ b/install.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 set -e
 set -u
diff --git a/readme.md b/readme.md
index f05be29..955ac35 100644
--- a/readme.md
+++ b/readme.md
@@ -52,7 +52,7 @@ Installation
 -------------
 Prerequisites:
 - tmux >= "v2.4"
-- OSX, Linux (tested on Ubuntu 14 and CentOS7)
+- OSX, Linux (tested on Ubuntu 14 and CentOS7), FreeBSD (tested on 11.1)
 
 Personally, I use it on OSX 10.11.5 El Capitan through iTerm2.
 
diff --git a/tmux/renew_env.sh b/tmux/renew_env.sh
index 0e51818..31a4b7c 100755
--- a/tmux/renew_env.sh
+++ b/tmux/renew_env.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 set -eu
 
diff --git a/tmux/yank.sh b/tmux/yank.sh
index 653e19f..83686c6 100755
--- a/tmux/yank.sh
+++ b/tmux/yank.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 set -eu
 
@@ -22,7 +22,9 @@ elif [ -n "${DISPLAY-}" ] && is_app_installed xsel; then
   copy_backend="xsel -i --clipboard"
 elif [ -n "${DISPLAY-}" ] && is_app_installed xclip; then
   copy_backend="xclip -i -f -selection primary | xclip -i -selection clipboard"
-elif [ -n "${copy_backend_remote_tunnel_port-}" ] && [ "$(ss -n -4 state listening "( sport = $copy_backend_remote_tunnel_port )" | tail -n +2 | wc -l)" -eq 1 ]; then
+elif [ -n "${copy_backend_remote_tunnel_port-}" ] \
+    && (netstat -f inet -nl 2>/dev/null || netstat -4 -nl 2>/dev/null) \
+      | grep -q "[.:]$copy_backend_remote_tunnel_port"; then
   copy_backend="nc localhost $copy_backend_remote_tunnel_port"
 fi