diff --git a/psu b/psu
index 724929b..c3ad6bb 100755
--- a/psu
+++ b/psu
@@ -128,25 +128,25 @@ main() {
     echo_debug_safe_json "Stack ${PORTAINER_STACK_NAME} -> $(echo $STACK | jq -C .)" "$STACK"
   fi
 
-  if [ $ACTION == "deploy" ]; then
+  if [ "$ACTION" == "deploy" ]; then
     deploy
     exit 0
   fi
 
-  if [ $ACTION == "rm" ]; then
+  if [ "$ACTION" == "rm" ]; then
     undeploy
     exit 0
   fi
 
-  if [ $ACTION == "login" ]; then
-    if [ $QUIET_MODE == "false" ] && [ $MASKED_VARIABLES == "false" ]; then
+  if [ "$ACTION" == "login" ]; then
+    if [ "$QUIET_MODE" == "false" ] && [ $MASKED_VARIABLES == "false" ]; then
       echo "$PORTAINER_AUTH_TOKEN"
     fi
     exit 0
   fi
 
   # Returns Docker system info
-  if [ $ACTION == "system:info" ]; then
+  if [ "$ACTION" == "system:info" ]; then
     local docker_info
     echo_verbose "Getting Docker info..."
     docker_info="$(docker_info)"
@@ -159,13 +159,13 @@ main() {
     exit 1
   fi
 
-  if [ $ACTION == "services" ]; then
+  if [ "$ACTION" == "services" ]; then
     echo_verbose "List service(s) of stack '$PORTAINER_STACK_NAME'..."
     local services
     services=$(services)
     echo_debug "Services action response -> $(echo $services | jq -C .)"
     if [ -n "$services" ] && [ ! "$services" == "[]" ]; then
-      if [ $QUIET_MODE == "false" ]; then
+      if [ "$QUIET_MODE" == "false" ]; then
         # Returns response in JSON format
         echo "$services"
       else
@@ -177,7 +177,7 @@ main() {
     exit 1
   fi
 
-  if [ $ACTION == "status" ]; then
+  if [ "$ACTION" == "status" ]; then
       echo_verbose "Status of tasks for the stack '$PORTAINER_STACK_NAME'..."
       local status
       # WIP: Each services should have at least one task
@@ -198,13 +198,13 @@ main() {
       fi
   fi
 
-  if [ $ACTION == "tasks" ] || [ $ACTION == "tasks:healthy" ]; then
+  if [ "$ACTION" == "tasks" ] || [ "$ACTION" == "tasks:healthy" ]; then
     local scope
-    scope="$(if [ $ACTION == "tasks:healthy" ]; then echo healthy; else echo all; fi)"
+    scope="$(if [ "$ACTION" == "tasks:healthy" ]; then echo healthy; else echo all; fi)"
     local tasks
     if [ -n "$PORTAINER_SERVICE_NAME" ]; then
       echo_verbose "List $scope tasks from service '$PORTAINER_SERVICE_NAME' of stack '$PORTAINER_STACK_NAME'..."
-      tasks=$(if [ $scope == "healthy" ]; then tasks_healthy; else tasks; fi)
+      tasks=$(if [ "$scope" == "healthy" ]; then tasks_healthy; else tasks; fi)
       echo_debug "Tasks action response -> $(echo $tasks | jq -C .)"
     else
       echo_verbose "List $scope tasks of stack '$PORTAINER_STACK_NAME'..."
@@ -228,7 +228,7 @@ main() {
     fi
 
     if [ -n "$tasks" ] && [ ! "$tasks" == "[]" ]; then
-      if [ $QUIET_MODE == "false" ]; then
+      if [ "$QUIET_MODE" == "false" ]; then
         # Returns response in JSON format
         echo "$tasks"
       else
@@ -241,13 +241,13 @@ main() {
     exit 1
   fi
 
-  if [ $ACTION == "containers" ]; then
+  if [ "$ACTION" == "containers" ]; then
     echo_verbose "List container(s) of stack '$PORTAINER_STACK_NAME'..."
     local containers
     containers=$(containers)
     echo_debug "Containers action response -> $(echo $containers | jq -C .)"
     if [ -n "$containers" ] && [ ! "$containers" == "[]" ]; then
-      if [ $QUIET_MODE == "false" ]; then
+      if [ "$QUIET_MODE" == "false" ]; then
         # Returns response in JSON format
         echo "$containers"
       else
@@ -261,9 +261,9 @@ main() {
 
   # Returns stack info
   # If it already exists
-  if [ $ACTION == "inspect" ]; then
+  if [ "$ACTION" == "inspect" ]; then
     if [ -n "$STACK" ]; then
-      if [ $QUIET_MODE == "false" ]; then
+      if [ "$QUIET_MODE" == "false" ]; then
         echo "$STACK"
       else
         # Only display the stack name in quiet mode
@@ -275,8 +275,8 @@ main() {
   fi
 
   # Get list of all stacks
-  if [ $ACTION == "ls" ]; then
-    if [ $QUIET_MODE == "false" ]; then
+  if [ "$ACTION" == "ls" ]; then
+    if [ "$QUIET_MODE" == "false" ]; then
       # Returns response in JSON format
       echo "$STACKS"
     else
@@ -287,13 +287,13 @@ main() {
   fi
 
   # Lint the Docker compose/stack file
-  if [ $ACTION == "lint" ]; then
+  if [ "$ACTION" == "lint" ]; then
     lint
     exit 0
   fi
 
   # Get list of all actions who can be used for this program
-  if [ $ACTION == "actions" ]; then
+  if [ "$ACTION" == "actions" ]; then
     echo "Portainer Stack Utils, version $VERSION"
     echo ""
     display_actions_message
@@ -571,7 +571,7 @@ inputs() {
           HTTPIE_VERIFY_SSL="${HTTPIE_VERIFY_SSL:-"yes"}"
         fi
         if [ "$HTTPIE_VERIFY_SSL" == "no" ] && [ -z "$PYTHONWARNINGS" ]; then
-          # Fix httpie with Debian and Ubuntu
+          # Fix HTTPie with Debian and Ubuntu
           export PYTHONWARNINGS="ignore:Unverified HTTPS request"
         fi
         if [ -n "$2" ] && [[ ! $2 =~ ^-.+$ ]] ; then
@@ -583,7 +583,7 @@ inputs() {
         echo_verbose "DEPRECATED: Use '--insecure' option, instead of this '$1' option"
         HTTPIE_VERIFY_SSL=$(input_flag "$1" "$2" "yes no" "no")
         if [ "$HTTPIE_VERIFY_SSL" == "no" ] && [ -z "$PYTHONWARNINGS" ]; then
-          # Fix httpie with Debian and Ubuntu
+          # Fix HTTPie with Debian and Ubuntu
           export PYTHONWARNINGS="ignore:Unverified HTTPS request"
         fi
         if [ -n "$2" ] && [[ ! $2 =~ ^-.+$ ]] ; then
@@ -851,7 +851,7 @@ echo_verbose() {
   local yellow='\033[1;33m'
   local nc='\033[0m'
 
-  if [ $VERBOSE_MODE == "true" ]; then
+  if [ "$VERBOSE_MODE" == "true" ]; then
     local verbose_message
     verbose_message=$(mask_variables "$message")
     echo -e "${yellow}${verbose_message}${nc}"
@@ -869,7 +869,7 @@ echo_verbose() {
 #########################################
 echo_debug() {
   local message=$1
-  if [ $DEBUG_MODE == "true" ]; then
+  if [ "$DEBUG_MODE" == "true" ]; then
     local debug_message
     debug_message=$(mask_variables "$message")
 
@@ -1027,7 +1027,7 @@ deploy() {
     echo_debug "Swarm ID -> $swarm_id"
 
     # If there is no swarm ID
-    if [ -z "$swarm_id" ];then
+    if [ -z "$swarm_id" ]; then
       echo_verbose "Swarm cluster not found."
 
       echo_verbose "Preparing stack JSON..."
@@ -1082,7 +1082,7 @@ deploy() {
 
     rm -f "$json_temp_path"
   else
-    if [ $STRICT_MODE == "true" ]; then
+    if [ "$STRICT_MODE" == "true" ]; then
       echo_error "Error: Stack $PORTAINER_STACK_NAME already exists."
       exit 1
     fi
@@ -1134,7 +1134,7 @@ deploy() {
 ##########################
 undeploy() {
   if [ -z "$STACK" ]; then
-    if [ $STRICT_MODE == "true" ]; then
+    if [ "$STRICT_MODE" == "true" ]; then
       echo_error "Error: Stack $PORTAINER_STACK_NAME does not exist."
       exit 1
     else
@@ -1332,7 +1332,7 @@ lint() {
 #   JSON string                                   #
 ###################################################
 env_file_to_json() {
-  echo "$(env -i sh -c "(unset \$(env | sed 's/=.*//'); set -a; . $(readlink -f $ENVIRONMENT_VARIABLES_FILE); set +a; jq -njc 'env | to_entries | map({name: .key, value: .value})')")"
+  env -i sh -c "(unset \$(env | sed 's/=.*//'); set -a; . $(readlink -f $ENVIRONMENT_VARIABLES_FILE); set +a; jq -njc 'env | to_entries | map({name: .key, value: .value})')"
 }
 
 # Set the ACTIONS variable who's a list of all psu actions
@@ -1487,7 +1487,7 @@ display_actions_message() {
     fi
   done
 
-  if [ $VERBOSE_MODE == "true" ]; then
+  if [ "$VERBOSE_MODE" == "true" ]; then
     display_actions_aliased_message
   fi
 }