diff --git a/scripts/upgrade b/scripts/upgrade
index b97cab1..b908949 100644
--- a/scripts/upgrade
+++ b/scripts/upgrade
@@ -43,11 +43,31 @@ ynh_clean_setup () {
 ynh_abort_if_errors
 
 #=================================================
-# ENSURE DOWNWARD COMPATIBILITY
+# CHECK VERSION
 #=================================================
 
 upgrade_type=$(ynh_check_app_version_changed)
 
+#=================================================
+# ENSURE DOWNWARD COMPATIBILITY
+#=================================================
+ynh_script_progression --message="Ensuring downward compatibility..." --weight=1
+
+### If nobody installed your app before 4.1,
+### then you may safely remove these lines
+
+# Cleaning legacy permissions
+if ynh_legacy_permissions_exists; then
+	ynh_legacy_permissions_delete_all
+
+	ynh_app_setting_delete --app=$app --key=is_public
+fi
+
+if ! ynh_permission_exists --permission="admin"; then
+	# Create the required permissions
+	ynh_permission_create --permission="admin" --url="/admin" --allowed=$admin
+fi
+
 #=================================================
 # CREATE DEDICATED USER
 #=================================================