diff --git a/files/validate_postgresql_connection.sh b/files/validate_postgresql_connection.sh
index f126d99..2b3d629 100644
--- a/files/validate_postgresql_connection.sh
+++ b/files/validate_postgresql_connection.sh
@@ -1,31 +1,34 @@
-#!/usr/bin/env bash
+#!/bin/sh
 
 # usage is: validate_db_connection 2 50 psql
 
 SLEEP=$1
 TRIES=$2
 PSQL=$3
 
 STATE=1
 
-for (( c=1; c<=$TRIES; c++ ))
+c=1
+
+while [ $c -le $TRIES ]
 do
   echo $c
   if [ $c -gt 1 ]
   then
     echo 'sleeping'
     sleep $SLEEP
   fi
 
   /bin/echo "SELECT 1" | $PSQL
   STATE=$?
 
   if [ $STATE -eq 0 ]
   then
     exit 0
   fi
+$c++
 done
 
 echo 'Unable to connect to postgresql'
 
 exit 1