diff --git a/frontend/src/utils/base-url-from-env-extractor.ts b/frontend/src/utils/base-url-from-env-extractor.ts
index 9ee57d0a0..2167c7d95 100644
--- a/frontend/src/utils/base-url-from-env-extractor.ts
+++ b/frontend/src/utils/base-url-from-env-extractor.ts
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2022 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
@@ -14,7 +14,7 @@ import { Optional } from '@mrdrogdrog/optional'
  */
 export class BaseUrlFromEnvExtractor {
   private baseUrls: Optional<BaseUrls> | undefined
-  private logger = new Logger('Base URL Configuration')
+  private readonly logger = new Logger('Base URL Configuration')
 
   private extractUrlFromEnvVar(envVarName: string, envVarValue: string | undefined): Optional<URL> {
     try {