diff --git a/src/helpers/mappings.ts b/src/helpers/mappings.ts
index 3761fff9b4b..852b95ca2a5 100644
--- a/src/helpers/mappings.ts
+++ b/src/helpers/mappings.ts
@@ -66,6 +66,7 @@ const extensionHighlight: Record<string, string> = {
 	md: 'markdown',
 	mkdown: 'markdown',
 	mkd: 'markdown',
+	log: 'plaintext',
 	nginxconf: 'nginx',
 	m: 'objectivec',
 	mm: 'objectivec',
diff --git a/src/tests/helpers/mappings.spec.ts b/src/tests/helpers/mappings.spec.ts
new file mode 100644
index 00000000000..49ca2296d42
--- /dev/null
+++ b/src/tests/helpers/mappings.spec.ts
@@ -0,0 +1,12 @@
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+import { extensionHighlight } from '../../helpers/mappings'
+
+describe('syntax highlight extension mappings', () => {
+	test('treats log files as plaintext', () => {
+		expect(extensionHighlight.log).toBe('plaintext')
+	})
+})