diff --git a/contract/test/ui-kit-goals/marshalTables.js b/contract/test/ui-kit-goals/marshalTables.js
index 3c658658..4dc8f4b5 100644
--- a/contract/test/ui-kit-goals/marshalTables.js
+++ b/contract/test/ui-kit-goals/marshalTables.js
@@ -38,10 +38,14 @@ const makeTranslationTable = (makeSlot, makeVal) => {
 const synthesizeRemotable = (slot, iface) =>
   Far(`${(iface ?? '').replace(/^Alleged: /, '')}#${slot}`, {});
 
-export const makeClientMarshaller = () => {
-  const { convertValToSlot, convertSlotToVal } = makeTranslationTable(val => {
+export const makeClientMarshaller = valToSlot => {
+  const noNewSlots = val => {
     throw new Error(`unknown value: ${val}`);
-  }, synthesizeRemotable);
+  };
+  const { convertValToSlot, convertSlotToVal } = makeTranslationTable(
+    valToSlot || noNewSlots,
+    synthesizeRemotable,
+  );
 
   return makeMarshal(convertValToSlot, convertSlotToVal, {
     serializeBodyFormat: 'smallcaps',