diff --git a/lib/default-profile.js b/lib/default-profile.js
index 5c2e3e49..a8cf3b6c 100644
--- a/lib/default-profile.js
+++ b/lib/default-profile.js
@@ -37,7 +37,7 @@ import {formatTravellers} from '../format/travellers.js';
 import {formatLoyaltyCard} from '../format/loyalty-cards.js';
 import {formatTransfers} from '../format/transfers.js';
 
-const DEBUG = (/(^|,)hafas-client(,|$)/).test(process.env.DEBUG || '');
+const DEBUG = (/(^|,)hafas-client(,|$)/).test(process?.env?.DEBUG ?? '');
 const logRequest = DEBUG
 	? (_, req, reqId) => console.error(String(req.body))
 	: () => { };