diff --git a/scripts/upgrade b/scripts/upgrade
index 1d10c85..f3c14c0 100755
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -4,20 +4,20 @@
 app=$YNH_APP_INSTANCE_NAME
 
 # Backup the current version of the app, restore it if the upgrade fails
-if sudo yunohost backup list | grep -q $app-before-upgrade > /dev/null 2>&1; then	# Supprime l'ancienne archive seulement si elle existe
-	sudo yunohost backup delete $app-before-upgrade
+if sudo yunohost backup list | grep -q ${app}-before-upgrade > /dev/null 2>&1; then     # Supprime l'ancienne archive seulement si e$
+        sudo yunohost backup delete ${app}-before-upgrade
 fi
-sudo yunohost backup create --ignore-hooks --apps $app --name $app-before-upgrade
+sudo yunohost backup create --ignore-hooks --apps $app --name ${app}-before-upgrade
 EXIT_PROPERLY () {
-	exit_code=$?
-	if [ "$exit_code" -eq 0 ]; then
-		exit 0	# Quitte sans erreur si le script se termine correctement.
-	fi
-	trap '' EXIT
-	set +eu
-	sudo yunohost app remove $app	# Supprime l'application avant de la restaurer.
-	sudo yunohost backup restore --ignore-hooks $app-before-upgrade --apps $app --force	# Restore the backup if upgrade failed
-	ynh_die "Upgrade failed. The app was restored to the way it was before the failed upgrade."
+        exit_code=$?
+        if [ "$exit_code" -eq 0 ]; then
+                exit 0  # Quitte sans erreur si le script se termine correctement.
+        fi
+        trap '' EXIT
+        set +eu
+        sudo yunohost app remove $app   # Supprime l'application avant de la restaurer.
+        sudo yunohost backup restore --ignore-hooks ${app}-before-upgrade --apps $app --force   # Restore the backup if upgrade fail$
+        ynh_die "Upgrade failed. The app was restored to the way it was before the failed upgrade."
 }
 set -eu
 trap EXIT_PROPERLY EXIT