diff --git a/scripts/upgrade b/scripts/upgrade
index 6a66c7a..2c72ad2 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -18,19 +18,19 @@ ynh_script_progression --message="Checking version..." --weight=1
 upgrade_type=$(ynh_check_app_version_changed)
 
 # If db_name doesn't exist, create it
-if [ -z "$db_name" ]; then
+if [ -z "${db_name:-}" ]; then
 	db_name=$(ynh_sanitize_dbid --db_name=$app)
 fi
 
 # If data_dir doesn't exist, create it
-if [ -z "$data_dir" ]; then
+if [ -z "${data_dir:-}" ]; then
 	data_dir=/home/yunohost.app/$app
 fi
 
 #=================================================
 # PHP-FPM CONFIGURATION
 #=================================================
-ynh_script_progression --message="Upgrading PHP-FPM configuration..." --weight=1
+ynh_script_progression --message="Upgrading system configurations related to $app..." --weight=1
 
 ynh_add_fpm_config
 
@@ -56,9 +56,9 @@ then
     	ynh_exec_as $app env PATH=$PATH drush @$app dis framaforms_spam
     	ynh_exec_as $app env PATH=$PATH drush @$app pm-uninstall framaforms_spam
 	popd
-	update-alternatives --set php /usr/bin/php${YNH_DEFAULT_PHP_VERSION}
-
+	update-alternatives --set php /usr/bin/php${YNH_PHP_VERSION}
 fi
+
 #=================================================
 # DOWNLOAD, CHECK AND UNPACK SOURCE
 #=================================================