diff --git a/frontend/src/lib/components/AddRelationshipForm.svelte.spec.ts b/frontend/src/lib/components/AddRelationshipForm.svelte.spec.ts
index 5dec75e3..9ddfd8a2 100644
--- a/frontend/src/lib/components/AddRelationshipForm.svelte.spec.ts
+++ b/frontend/src/lib/components/AddRelationshipForm.svelte.spec.ts
@@ -37,4 +37,20 @@ describe('AddRelationshipForm', () => {
 		document.querySelector<HTMLButtonElement>('button')!.click();
 		await expect.element(page.getByRole('button', { name: /^Hinzufügen$/i })).toBeDisabled();
 	});
+
+	it('shows year-range error when toYear is before fromYear', async () => {
+		render(AddRelationshipForm, { personId: 'person-1' });
+		document.querySelector<HTMLButtonElement>('button')!.click();
+		await expect.element(page.getByRole('combobox')).toBeInTheDocument();
+
+		const fromInput = document.querySelector<HTMLInputElement>('input[name="fromYear"]')!;
+		fromInput.value = '1935';
+		fromInput.dispatchEvent(new InputEvent('input', { bubbles: true }));
+
+		const toInput = document.querySelector<HTMLInputElement>('input[name="toYear"]')!;
+		toInput.value = '1920';
+		toInput.dispatchEvent(new InputEvent('input', { bubbles: true }));
+
+		await expect.element(page.getByRole('alert')).toBeVisible();
+	});
 });