From f503760ace6f259deec3d0e466850cdab8436b53 Mon Sep 17 00:00:00 2001
From: Max Klenk <max@klenk.biz>
Date: Fri, 25 Sep 2026 23:08:57 +0200
Subject: [PATCH] fix(coins): correct EIP-55 checksum of USDT0 on Rootstock

---
 .changeset/fix-usdt0-rootstock-checksum.md |  5 ++++
 src/coins/coins.ts                         |  2 +-
 src/coins/coins.unit.spec.ts               | 33 ++++++++++++++++++++++
 3 files changed, 39 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/fix-usdt0-rootstock-checksum.md
 create mode 100644 src/coins/coins.unit.spec.ts

diff --git a/.changeset/fix-usdt0-rootstock-checksum.md b/.changeset/fix-usdt0-rootstock-checksum.md
new file mode 100644
index 0000000..41cbf21
--- /dev/null
+++ b/.changeset/fix-usdt0-rootstock-checksum.md
@@ -0,0 +1,5 @@
+---
+"@lifi/data-types": patch
+---
+
+Fix the EIP-55 checksum of the USDT0 address on Rootstock, which was mis-cased and rejected by address lookups that compare verbatim.
diff --git a/src/coins/coins.ts b/src/coins/coins.ts
index 506c941..60c6fc9 100644
--- a/src/coins/coins.ts
+++ b/src/coins/coins.ts
@@ -3017,7 +3017,7 @@ export const basicCoins: BasicCoin[] = [
         decimals: 6,
       },
       [ChainId.RSK]: {
-        address: '0x779dED0C9e1022225F8e0630b35A9B54Be713736',
+        address: '0x779Ded0c9e1022225f8E0630b35a9b54bE713736',
         decimals: 6,
       },
       [ChainId.ARB]: {
diff --git a/src/coins/coins.unit.spec.ts b/src/coins/coins.unit.spec.ts
new file mode 100644
index 0000000..c48bc0f
--- /dev/null
+++ b/src/coins/coins.unit.spec.ts
@@ -0,0 +1,33 @@
+import type { StaticToken } from '@lifi/types'
+import { isAddress } from 'viem'
+import { describe, expect, it } from 'vitest'
+import { supportedEVMChains } from '../chains/supportedChains.evm.js'
+import { defaultCoins, wrappedTokens } from './coins.js'
+
+const evmChainIds = new Set(supportedEVMChains.map((chain) => chain.id))
+
+const evmTokens: StaticToken[] = [
+  ...defaultCoins.flatMap((coin) => Object.values(coin.chains)),
+  ...Object.values(wrappedTokens),
+].filter((token) => evmChainIds.has(token.chainId))
+
+describe('validate EVM token addresses', () => {
+  it('has tokens to check', () => {
+    expect(evmTokens.length).toBeGreaterThan(0)
+  })
+
+  // A mixed-case address carries its own EIP-55 checksum, so a typo in the
+  // casing makes it invalid. Services that compare addresses verbatim then
+  // fail to resolve the token instead of silently normalising it. All-lowercase
+  // addresses carry no checksum and stay valid.
+  it('are valid EIP-55 addresses', () => {
+    const invalid = evmTokens
+      .filter((token) => !isAddress(token.address, { strict: true }))
+      .map(
+        (token) =>
+          `${token.coinKey} on chain ${token.chainId}: ${token.address}`
+      )
+
+    expect(invalid).toEqual([])
+  })
+})