diff --git a/static/give/afac26.html b/static/give/afac26.html
index d5edd37..2c5acc9 100644
--- a/static/give/afac26.html
+++ b/static/give/afac26.html
@@ -149,7 +149,18 @@
             history.replaceState({}, '', location.pathname);
         }
 
+        const amountParam = params.get('a');
         let selectedDonation = 10;
+        if (amountParam) {
+            const amount = parseFloat(amountParam);
+            if (amount > 0) {
+                document.getElementById('custom-amount').value = amount % 1 === 0 ? amount : amount.toFixed(2);
+                const group = document.getElementById('donation-group');
+                group.querySelectorAll('wa-button').forEach(b => b.classList.remove('selected'));
+                group.querySelector('wa-button[data-value="custom"]').classList.add('selected');
+                selectedDonation = 'custom';
+            }
+        }
 
         function setupButtonGroup(groupId, onChange) {
             const group = document.getElementById(groupId);
@@ -178,7 +189,7 @@
         donateBtn.addEventListener('click', async () => {
             let donationCents = 0;
             if (selectedDonation === 'custom') {
-                donationCents = (parseInt(document.getElementById('custom-amount').value) || 0) * 100;
+                donationCents = Math.round((parseFloat(document.getElementById('custom-amount').value) || 0) * 100);
             } else {
                 donationCents = selectedDonation * 100;
             }