diff --git a/scripts/change_url b/scripts/change_url
index 1ce94241..6e2df58b 100644
--- a/scripts/change_url
+++ b/scripts/change_url
@@ -53,7 +53,7 @@ ynh_print_info --message="Updating nginx web server configuration..."
 nginx_conf_path=/etc/nginx/conf.d/$old_domain.d/$app.conf
 
 # Change the domain for nginx
-if [ $change_domain -eq 1 ]
+if [ "$change_domain" -eq 1 ]
 then
 	# Delete file checksum for the old conf file location
 	ynh_delete_file_checksum --file="$nginx_conf_path"
diff --git a/scripts/install b/scripts/install
index 01a955c8..1bd26616 100644
--- a/scripts/install
+++ b/scripts/install
@@ -102,7 +102,7 @@ ynh_add_nginx_config
 ynh_print_info --message="Configuring system user..."
 
 # Create a system user
-ynh_system_user_create "$app"
+ynh_system_user_create --username="$app"
 
 #=================================================
 # PHP-FPM CONFIGURATION
diff --git a/scripts/upgrade b/scripts/upgrade
index babf65d8..c8c33017 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -121,7 +121,7 @@ ynh_install_php --phpversion="7.2" --package="$extra_pkg_dependencies"
 ynh_print_info --message="Making sure dedicated system user exists..."
 
 # Create a dedicated user (if not existing)
-ynh_system_user_create "$app"
+ynh_system_user_create --username="$app"
 
 #=================================================
 # PHP-FPM CONFIGURATION
@@ -195,7 +195,7 @@ chown -R "$app": "$final_path"
 ynh_print_info --message="Upgrading SSOwat configuration..."
 
 # Make app public if necessary
-if [ $is_public -eq 1 ]
+if [ "$is_public" -eq 1 ]
 then
 	# unprotected_uris allows SSO credentials to be passed anyway
 	ynh_app_setting_set --app="$app" --key=unprotected_uris --value="/"