diff --git a/scripts/_common.sh b/scripts/_common.sh
index 2b3762c..e59c7f7 100644
--- a/scripts/_common.sh
+++ b/scripts/_common.sh
@@ -149,7 +149,7 @@ EOF
 # Used by update_config_if_needed.sh hook
 save_vars_current_value() {
     for var in $var_list_to_manage; do
-        ynh_app_setting_set --app="$app" --key=previous_$var --value="${!var}"
+        ynh_app_setting_set --app="$app" --key="previous_$var" --value="${!var}"
     done
 }
 
diff --git a/scripts/backup b/scripts/backup
index 02e89fd..d48d15c 100755
--- a/scripts/backup
+++ b/scripts/backup
@@ -15,7 +15,7 @@ load_vars
 #=================================================
 # STOP SYSTEMD SERVICE
 #=================================================
-if systemctl is-active $app.service --quiet; then
+if systemctl is-active "$app".service --quiet; then
     ynh_print_warn --message="It's highly recommended to make your backup when the service is stopped. Please stop $app service with this command before to run the backup 'systemctl stop $app.service'"
 fi
 
@@ -33,7 +33,7 @@ ynh_backup --src_path="/etc/nginx/conf.d/$domain.d/$app.conf"
 ynh_backup --src_path="$nginx_status_conf"
 
 ynh_print_info --message="Backing up code..."
-ynh_backup --src_path=$install_dir
+ynh_backup --src_path="$install_dir"
 
 #=================================================
 # SPECIFIC BACKUP
diff --git a/scripts/change_url b/scripts/change_url
index 8e33286..5048134 100644
--- a/scripts/change_url
+++ b/scripts/change_url
@@ -18,7 +18,7 @@ load_vars
 #=================================================
 ynh_script_progression --message="Stopping a systemd service..." --weight=1
 
-ynh_systemd_action --service_name=$app --action="stop" --log_path="/var/log/$app/$app.log"
+ynh_systemd_action --service_name="$app" --action="stop" --log_path="/var/log/$app/$app.log"
 
 #=================================================
 # MODIFY URL IN NGINX CONF
diff --git a/scripts/install b/scripts/install
index 16ba4fe..bb84c97 100755
--- a/scripts/install
+++ b/scripts/install
@@ -17,10 +17,10 @@ ensure_vars_set
 # Check datadir empty
 #=================================================
 
-if [ -n "$(ls -A $data_dir)" ]; then
+if [ -n "$(ls -A "$data_dir")" ]; then
     old_data_dir_path="${data_dir}_$(date '+%Y%m%d.%H%M%S')"
     ynh_print_warn --message="Data directory was not empty. Data was moved to $old_data_dir_path"
-    mkdir -p $old_data_dir_path
+    mkdir -p "$old_data_dir_path"
     mv -t "$old_data_dir_path" "$data_dir"/*
     app_data_dirs="$(echo /home/yunohost.app/*)"
 fi
diff --git a/scripts/remove b/scripts/remove
index 5204395..bd84296 100755
--- a/scripts/remove
+++ b/scripts/remove
@@ -18,7 +18,7 @@ load_vars
 #=================================================
 
 # Remove the service from the list of services known by YunoHost (added from `yunohost service add`)
-if ynh_exec_warn_less yunohost service status $app >/dev/null
+if ynh_exec_warn_less yunohost service status "$app" >/dev/null
 then
     ynh_script_progression --message="Removing $app service integration..." --weight=3
     yunohost service remove "$app"
@@ -48,11 +48,11 @@ for pool_dir_by_version in /etc/php/*; do
     fi
 done
 
-if ynh_psql_user_exists --user=$db_user; then
-    ynh_psql_drop_user $db_user
+if ynh_psql_user_exists --user="$db_user"; then
+    ynh_psql_drop_user "$db_user"
 fi
-if ynh_mysql_user_exists --user=$db_user; then
-    ynh_mysql_drop_user $db_user
+if ynh_mysql_user_exists --user="$db_user"; then
+    ynh_mysql_drop_user "$db_user"
 fi
 
 ynh_package_autopurge monitorix
diff --git a/scripts/upgrade b/scripts/upgrade
index e051fa3..5984372 100755
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -11,7 +11,7 @@ source experimental_helper.sh
 source /usr/share/yunohost/helpers
 load_vars
 
-upgrade_type=$(ynh_check_app_version_changed)
+upgrade_type="$(ynh_check_app_version_changed)"
 
 #=================================================
 # STANDARD UPGRADE STEPS
@@ -30,14 +30,14 @@ ynh_script_progression --message="Ensuring downward compatibility..." --weight=1
 test -e /etc/monitorix/conf.d/00-debian.conf || touch /etc/monitorix/conf.d/00-debian.conf
 
 # Remove old hook if exist
-ynh_secure_remove --file=/usr/share/yunohost/hooks/post_iptable_rules/50-$app
+ynh_secure_remove --file=/usr/share/yunohost/hooks/post_iptable_rules/50-"$app"
 
 #=================================================
 # STOP SYSTEMD SERVICE
 #=================================================
 ynh_script_progression --message="Stopping a systemd service..." --weight=1
 
-ynh_systemd_action --service_name=$app --action=stop --log_path="/var/log/$app/$app.log"
+ynh_systemd_action --service_name="$app" --action=stop --log_path="/var/log/$app/$app.log"
 
 #=================================================
 # "REBUILD" THE APP (DEPLOY NEW SOURCES, RERUN NPM BUILD...)