diff --git a/frontend/src/routes/DocumentList.svelte b/frontend/src/routes/DocumentList.svelte
index 4a16b6eb..78aaa09e 100644
--- a/frontend/src/routes/DocumentList.svelte
+++ b/frontend/src/routes/DocumentList.svelte
@@ -30,7 +30,9 @@ let {
 	sort?: string;
 } = $props();
 
-const fallbackLabel = $derived(sort === 'DATE' ? m.docs_group_undated() : m.docs_group_unknown());
+const fallbackLabel = $derived(
+	(sort ?? 'DATE') === 'DATE' ? m.docs_group_undated() : m.docs_group_unknown()
+);
 const groupedDocuments = $derived.by(() =>
 	groupDocuments(documents, sort ?? 'DATE', fallbackLabel)
 );
diff --git a/frontend/src/routes/DocumentList.svelte.spec.ts b/frontend/src/routes/DocumentList.svelte.spec.ts
index 1d7d728b..224501e5 100644
--- a/frontend/src/routes/DocumentList.svelte.spec.ts
+++ b/frontend/src/routes/DocumentList.svelte.spec.ts
@@ -90,6 +90,15 @@ describe('DocumentList – group headers', () => {
 		await expect.element(page.getByTestId('group-divider')).not.toBeInTheDocument();
 	});
 
+	it('shows Undatiert fallback label when sort is undefined and doc has no date', async () => {
+		const documents = [
+			makeDoc({ id: '1', documentDate: '1938-01-01' }),
+			makeDoc({ id: '2', documentDate: null })
+		];
+		render(DocumentList, { ...baseProps, documents, total: 2 }); // sort omitted — defaults to DATE grouping
+		await expect.element(page.getByText(/UNDATIERT/i)).toBeInTheDocument();
+	});
+
 	it('a doc with two receivers appears in both receiver groups', async () => {
 		const documents = [
 			makeDoc({