diff --git a/check_mongo.sh b/check_mongo.sh
index b02563a..b38b996 100755
--- a/check_mongo.sh
+++ b/check_mongo.sh
@@ -4,16 +4,16 @@ machine=${1:-0}
 model=${2:-controller}
 
 read -d '' -r cmds <<'EOF'
-conf=/var/lib/juju/agents/machine-*/agent.conf
-user=`sudo grep tag $conf | cut -d' ' -f2`
-password=`sudo grep statepassword $conf | cut -d' ' -f2`
+user=$(sudo ls /var/lib/juju/agents/)
+conf=/var/lib/juju/agents/${user}/agent.conf
+password=$(sudo grep statepassword ${conf} | cut -d' ' -f2)
 if [ -f /usr/lib/juju/mongo*/bin/mongo ]; then
   client=/usr/lib/juju/mongo*/bin/mongo
 else
   client=/usr/bin/mongo
 fi
-$client 127.0.0.1:37017/juju --authenticationDatabase admin --ssl --sslAllowInvalidCertificates --username "$user" --password "$password"
+${client} 127.0.0.1:37017/juju --authenticationDatabase admin --ssl --sslAllowInvalidCertificates --username "${user}" --password "${password}"
 EOF
 
-juju ssh -m $model $machine "$cmds"
+juju ssh -m ${model} ${machine} "${cmds}"