diff --git a/frontend/src/lib/components/payments/UserPaymentModal.svelte b/frontend/src/lib/components/payments/UserPaymentModal.svelte
index 06235b9..c47cc28 100644
--- a/frontend/src/lib/components/payments/UserPaymentModal.svelte
+++ b/frontend/src/lib/components/payments/UserPaymentModal.svelte
@@ -217,10 +217,7 @@
 	// state. The backend will split the charge into deposit + non-deposit records
 	// when appropriate, so this choice mainly controls the button label and amount.
 	const defaultType = $derived(defaultPaymentType ?? (depositOutstanding ? 'deposit' : 'full'));
-	let paymentType = $state<'full' | 'partial' | 'deposit'>('full');
-	$effect(() => {
-		paymentType = defaultType as 'full' | 'partial' | 'deposit';
-	});
+	let paymentType = $derived.writable(defaultType as 'full' | 'partial' | 'deposit');
 
 	let pollingInterval: ReturnType<typeof setInterval> | null = null;