diff --git a/packages/fast-usdc/src/exos/operator-kit.js b/packages/fast-usdc/src/exos/operator-kit.js
index b5e847f30d5..310b10ad0a9 100644
--- a/packages/fast-usdc/src/exos/operator-kit.js
+++ b/packages/fast-usdc/src/exos/operator-kit.js
@@ -35,7 +35,7 @@ const OperatorKitI = {
   }),
 
   operator: M.interface('Operator', {
-    submitEvidence: M.call(CctpTxEvidenceShape).returns(M.promise()),
+    submitEvidence: M.call(CctpTxEvidenceShape).returns(),
     getStatus: M.call().returns(M.record()),
   }),
 };
@@ -87,7 +87,7 @@ export const prepareOperatorKit = (zone, staticPowers) =>
           const { operator } = this.facets;
           // TODO(bootstrap integration): cause this call to throw and confirm that it
           // shows up in the the smart-wallet UpdateRecord `error` property
-          await operator.submitEvidence(evidence);
+          operator.submitEvidence(evidence);
           return staticPowers.makeInertInvitation(
             'evidence was pushed in the invitation maker call',
           );
@@ -98,12 +98,12 @@ export const prepareOperatorKit = (zone, staticPowers) =>
          * submit evidence from this operator
          *
          * @param {CctpTxEvidence} evidence
+         * @returns {void}
          */
-        async submitEvidence(evidence) {
+        submitEvidence(evidence) {
           const { state } = this;
           !state.disabled || Fail`submitEvidence for disabled operator`;
-          const result = state.powers.attest(evidence, this.facets);
-          return result;
+          state.powers.attest(evidence, this.facets);
         },
         /** @returns {OperatorStatus} */
         getStatus() {
diff --git a/packages/fast-usdc/test/exos/transaction-feed.test.ts b/packages/fast-usdc/test/exos/transaction-feed.test.ts
index 64c6f8c34a1..9f1c902aaae 100644
--- a/packages/fast-usdc/test/exos/transaction-feed.test.ts
+++ b/packages/fast-usdc/test/exos/transaction-feed.test.ts
@@ -48,12 +48,9 @@ test('happy aggregation', async t => {
 
   const { op1, op2, op3 } = await makeOperators(feedKit);
   const evidence = MockCctpTxEvidences.AGORIC_PLUS_OSMO();
-  const results = await Promise.all([
-    op1.operator.submitEvidence(evidence),
-    op2.operator.submitEvidence(evidence),
-    op3.operator.submitEvidence(evidence),
-  ]);
-  t.deepEqual(results, [undefined, undefined, undefined]);
+  op1.operator.submitEvidence(evidence);
+  op2.operator.submitEvidence(evidence);
+  op3.operator.submitEvidence(evidence);
 
   const accepted = await evidenceSubscriber.getUpdateSince(0);
   t.deepEqual(accepted, {
@@ -62,18 +59,17 @@ test('happy aggregation', async t => {
   });
 
   // verify that it doesn't publish until three match
-  await Promise.all([
-    // once it publishes, it doesn't remember that it already saw these
-    op1.operator.submitEvidence(evidence),
-    op2.operator.submitEvidence(evidence),
-    // but this time the third is different
-    op3.operator.submitEvidence(MockCctpTxEvidences.AGORIC_PLUS_DYDX()),
-  ]);
+  // once it publishes, it doesn't remember that it already saw these
+  op1.operator.submitEvidence(evidence);
+  op2.operator.submitEvidence(evidence);
+  // but this time the third is different
+  op3.operator.submitEvidence(MockCctpTxEvidences.AGORIC_PLUS_DYDX());
+
   t.like(await evidenceSubscriber.getUpdateSince(0), {
     // Update count is still 1
     updateCount: 1n,
   });
-  await op3.operator.submitEvidence(evidence);
+  op3.operator.submitEvidence(evidence);
   t.like(await evidenceSubscriber.getUpdateSince(0), {
     updateCount: 2n,
   });
@@ -85,11 +81,11 @@ test('disabled operator', async t => {
   const evidence = MockCctpTxEvidences.AGORIC_PLUS_OSMO();
 
   // works before disabling
-  await op1.operator.submitEvidence(evidence);
+  op1.operator.submitEvidence(evidence);
 
   op1.admin.disable();
 
-  await t.throwsAsync(() => op1.operator.submitEvidence(evidence), {
+  t.throws(() => op1.operator.submitEvidence(evidence), {
     message: 'submitEvidence for disabled operator',
   });
 });