diff --git a/src/components/TimedOrderEntry.vue b/src/components/TimedOrderEntry.vue
index 5384a8e..3b499b9 100644
--- a/src/components/TimedOrderEntry.vue
+++ b/src/components/TimedOrderEntry.vue
@@ -260,8 +260,9 @@ async function placeOrder() {
   } else {
     window = duration / n
   }
-  const ceil = 10n ** 18n % BigInt(n) ? 1n : 0n
-  const amtPerTranche = 10n ** 18n / BigInt(n) + ceil
+  const oneHundredPercent = 65535n // by contract definition of uint16 fraction
+  const ceil = oneHundredPercent % BigInt(n) ? 1n : 0n
+  const amtPerTranche = oneHundredPercent / BigInt(n) + ceil
   duration -= 15  // subtract 15 seconds so the last tranche completes before the deadline
   for (let i = 0; i < n; i++) {
     const start = Math.floor(i * (duration / n))