diff --git a/scripts/change_url b/scripts/change_url
index 0f44907..1b13b23 100644
--- a/scripts/change_url
+++ b/scripts/change_url
@@ -23,6 +23,8 @@ ynh_systemd_action --service_name=$app --action="stop" --log_path=systemd
 #=================================================
 ynh_script_progression --message="Updating NGINX web server configuration..." --weight=1
 
+python_venv_site_packages=$(__ynh_python_venv_get_site_packages_dir -d "$install_dir/venv")
+
 ynh_change_url_nginx_config
 
 #=================================================
diff --git a/scripts/upgrade b/scripts/upgrade
index fc1af46..5820447 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -70,7 +70,7 @@ if [[ "$upgrade_from_opt" == "true" ]]; then
 fi
 
 # If secret_key doesn't exist, create it
-if [ -z "$secret_key" ]; then
+if [ -z "${secret_key:-}" ]; then
 	secret_key=$(ynh_string_random --length=32)
 	ynh_app_setting_set --app=$app --key=secret_key --value=$secret_key
 fi