diff --git a/add-virtual-user.sh b/add-virtual-user.sh
index a5bd71c..848f96b 100755
--- a/add-virtual-user.sh
+++ b/add-virtual-user.sh
@@ -2,22 +2,22 @@
 
 set -e
 
-[ "$DEBUG" == 'true' ] && set -x
+[[ "${DEBUG}" == 'true' ]] && set -x
 
 DB=/etc/vsftpd/virtual-users.db
 
-if [ "$#" -lt 2 ] || [ "$#" -gt 3 ]; then
-    echo "Usage: $0 [-d] <user> <password>" >&2
-    echo >&2
-    echo "[ -d ] Delete the database first" >&2
-    exit 1
+if [[ "$#" -lt 2 || "$#" -gt 3 ]]; then
+  echo "Usage: $0 [-d] <user> <password>" >&2
+  echo >&2
+  echo "[ -d ] Delete the database first" >&2
+  exit 1
 fi
 
-if [ "$1" == "-d" ]; then
-    if [ -f $DB ]; then
-        rm $DB
-    fi
-    shift
+if [[ "${1}" == "-d" ]]; then
+  if [[ -f "${DB}" ]]; then
+    rm "${DB}"
+  fi
+  shift
 fi
 
-echo -e "$1\n$2" | db5.3_load -T -t hash $DB
+echo -e "${1}\n${2}" | db5.3_load -T -t hash "${DB}"
diff --git a/entry.sh b/entry.sh
index 9459881..bc5ba2e 100755
--- a/entry.sh
+++ b/entry.sh
@@ -2,33 +2,34 @@
 
 set -e
 
-[ "$DEBUG" == 'true' ] && set -x
+[[ "${DEBUG}" == 'true' ]] && set -x
 
 # Generate password if hash not set
-if [ ! -z "$FTP_PASSWORD" -a -z "$FTP_PASSWORD_HASH" ]; then
-  FTP_PASSWORD_HASH=$(echo "$FTP_PASSWORD" | mkpasswd -s -m sha-512)
+if [[ ! -z "${FTP_PASSWORD}" && -z "${FTP_PASSWORD_HASH}" ]]; then
+  FTP_PASSWORD_HASH=$(echo "${FTP_PASSWORD}" | mkpasswd -s -m sha-512)
 fi
 
-if [ ! -z "$FTP_USER" -a ! -z "$FTP_PASSWORD_HASH" ]; then
-    /add-virtual-user.sh -d "$FTP_USER" "$FTP_PASSWORD_HASH"
+if [[ ! -z "${FTP_USER}" && ! -z "${FTP_PASSWORD_HASH}" ]]; then
+  echo "Adding user ${FTP_USER}"
+  /add-virtual-user.sh -d "${FTP_USER}" "${FTP_PASSWORD_HASH}"
 fi
 
 # Support multiple users
 while read user; do
-	IFS=: read name pass <<< ${!user}
-	echo "Adding user $name"
-	/add-virtual-user.sh "$name" "$pass"
+  IFS=: read name pass <<< "${!user}"
+  echo "Adding user ${name}"
+  /add-virtual-user.sh "${name}" "${pass}"
 done < <(env | grep "FTP_USER_" | sed 's/^\(FTP_USER_[a-zA-Z0-9]*\)=.*/\1/')
 
 # Support user directories
-if [ ! -z "$FTP_USERS_ROOT" ]; then
-	sed -i 's/local_root=.*/local_root=\/srv\/$USER/' /etc/vsftpd*.conf
+if [[ ! -z "${FTP_USERS_ROOT}" ]]; then
+  sed -i 's/local_root=.*/local_root=\/srv\/$USER/' "/etc/vsftpd*.conf"
 fi
 
-function vsftpd_stop {
+vsftpd_stop() {
   echo "Received SIGINT or SIGTERM. Shutting down vsftpd"
   # Get PID
-  pid=$(cat /var/run/vsftpd/vsftpd.pid)
+  pid="$(cat /var/run/vsftpd/vsftpd.pid)"
   # Set TERM
   kill -SIGTERM "${pid}"
   # Wait for exit
@@ -37,7 +38,7 @@ function vsftpd_stop {
   echo "Done"
 }
 
-if [ "$1" == "vsftpd" ]; then
+if [[ "$1" == "vsftpd" ]]; then
   trap vsftpd_stop SIGINT SIGTERM
   echo "Running $@"
   $@ &