diff --git a/src/blockchain/mint-ticket.processor.spec.ts b/src/blockchain/mint-ticket.processor.spec.ts
index 519de92..fffb94f 100644
--- a/src/blockchain/mint-ticket.processor.spec.ts
+++ b/src/blockchain/mint-ticket.processor.spec.ts
@@ -1,6 +1,7 @@
 import { BlockchainTxType, WalletCreationStatus } from '@prisma/client';
 import type { Job } from 'bullmq';
 import { MintTicketProcessor } from './mint-ticket.processor';
+import { FEE_TYPE_USDC } from './onchain-fees';
 import { MINT_TICKET_JOB, MintTicketJobData } from './mint-queue.service';
 
 // getChain is env-driven; stub the USDC + Diamond addresses.
@@ -83,8 +84,12 @@ describe('MintTicketProcessor', () => {
 
     await m.proc.process(job());
 
-    // Authoritative on-chain fee read for the USDC feeType (5).
-    expect(m.getAllFees).toHaveBeenCalledWith('BASE-SEPOLIA', 7n, 5);
+    // Authoritative on-chain fee read for the crypto settlement feeType.
+    expect(m.getAllFees).toHaveBeenCalledWith(
+      'BASE-SEPOLIA',
+      7n,
+      FEE_TYPE_USDC,
+    );
     // Approve the Diamond to pull exactly totalFee from the buyer wallet.
     expect(m.approveErc20).toHaveBeenCalledWith(
       expect.objectContaining({
@@ -98,7 +103,7 @@ describe('MintTicketProcessor', () => {
     expect(m.executeContract).toHaveBeenCalledWith(
       expect.objectContaining({
         method: 'mintTicket',
-        args: [7n, 5, '0xBUYER'],
+        args: [7n, FEE_TYPE_USDC, '0xBUYER'],
         walletId: 'cw-buyer',
         txType: BlockchainTxType.MINT,
         existingBlockchainTransactionId: 'bt-1',
diff --git a/src/blockchain/onchain-fees.ts b/src/blockchain/onchain-fees.ts
index 7d02c13..9df818c 100644
--- a/src/blockchain/onchain-fees.ts
+++ b/src/blockchain/onchain-fees.ts
@@ -19,8 +19,21 @@ export const FEE_TYPE_BY_NAME: Record<string, number> = {
   LSK: 10,
 };
 
-/** On-chain FeeType code for USDC — HostIT's crypto settlement token. */
-export const FEE_TYPE_USDC = FEE_TYPE_BY_NAME.USDC;
+/**
+ * ⚠️ TEMPORARY TESTNET WORKAROUND — revert after the Diamond is redeployed.
+ *
+ * The deployed Base Sepolia Diamond has the real USDC token address
+ * registered under the **USDT (4)** slot; `FeeType.USDC (5)` is UNSET, so
+ * `mintTicket(…, USDC, …)` reverts `TokenAddressZero()`. Until a redeploy
+ * maps USDC (5) → 0x036CbD5…, we route crypto settlement (publish fee +
+ * approve + mintTicket) through the USDT slot, which resolves to the USDC
+ * token on-chain. Flip `SETTLEMENT_FEE_TYPE_NAME` back to `'USDC'` once the
+ * contract is fixed. Tracked in epic #96.
+ */
+export const SETTLEMENT_FEE_TYPE_NAME = 'USDT';
+
+/** On-chain FeeType code used for crypto (USDC) settlement. */
+export const FEE_TYPE_USDC = FEE_TYPE_BY_NAME[SETTLEMENT_FEE_TYPE_NAME];
 
 /** USDC is 6-decimal everywhere Circle issues it. */
 export const USDC_DECIMALS = 6;
diff --git a/src/events/events.service.ts b/src/events/events.service.ts
index 0967c67..1045e2b 100644
--- a/src/events/events.service.ts
+++ b/src/events/events.service.ts
@@ -20,7 +20,10 @@ import {
   Prisma,
 } from '@prisma/client';
 import * as crypto from 'crypto';
-import { computeUsdcFees } from '../blockchain/onchain-fees';
+import {
+  computeUsdcFees,
+  SETTLEMENT_FEE_TYPE_NAME,
+} from '../blockchain/onchain-fees';
 
 @Injectable()
 export class EventsService {
@@ -536,10 +539,11 @@ export class EventsService {
         symbol: `${eventSymbol}-${tt.name.replace(/\s+/g, '').slice(0, 4).toUpperCase()}`,
         uri: `https://api.hostit.ng/events/${event.slug}/${tt.id}/metadata`,
       },
-      // Crypto checkout settles in USDC via `mintTicket`. Free events
-      // ignore fees on-chain (createTicket skips setTicketFees when
-      // isFree), so the converted value is harmless there.
-      feeTypes: ['USDC'],
+      // Crypto checkout settles in USDC via `mintTicket`. The on-chain fee
+      // slot is `SETTLEMENT_FEE_TYPE_NAME` (temporarily USDT — see
+      // onchain-fees.ts). Free events ignore fees on-chain (createTicket
+      // skips setTicketFees when isFree), so the value is harmless there.
+      feeTypes: [SETTLEMENT_FEE_TYPE_NAME],
       prices: [computeUsdcFees(tt.price, usdcNgnRate).ticketFee],
     }));