diff --git a/packages/batch-read-ts/src/index.ts b/packages/batch-read-ts/src/index.ts
index 268d345..db0c430 100644
--- a/packages/batch-read-ts/src/index.ts
+++ b/packages/batch-read-ts/src/index.ts
@@ -24,12 +24,13 @@ async function main() {
   const multicallAddress = DeployOut.multicall as `0x${string}`;
   const tokenAddresses = DeployOut.tokens as `0x${string}`[];
 
-  const { client, account } = await createClient(alicePrivateKey, mode);
+  const { client, account, chain } = await createClient(alicePrivateKey, mode);
   const expiry = createExpiry(1);
   const signature = await signBalanceRead(
     alicePrivateKey,
     account.address,
     expiry,
+    chain.id,
   );
 
   console.log(`Network: ${mode}`);
diff --git a/packages/batch-read-ts/src/util/signature.test.ts b/packages/batch-read-ts/src/util/signature.test.ts
new file mode 100644
index 0000000..22449b6
--- /dev/null
+++ b/packages/batch-read-ts/src/util/signature.test.ts
@@ -0,0 +1,71 @@
+import { test, expect } from "bun:test";
+import {
+  type Hex,
+  type Address,
+  keccak256,
+  encodeAbiParameters,
+  concat,
+  recoverAddress,
+  toHex,
+} from "viem";
+import { privateKeyToAccount } from "viem/accounts";
+
+import { signBalanceRead } from "./signature";
+
+// Fixed vector so the EIP-712 digest is deterministic across runs.
+const PRIVATE_KEY =
+  "0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80" as Hex;
+const OWNER = privateKeyToAccount(PRIVATE_KEY).address as Address;
+const EXPIRY = 1893456000n; // 2030-01-01T00:00:00Z
+const CHAIN_ID = 5124n; // seismic devnet/testnet chain id
+
+// Reconstruct the EIP-712 digest per seismic-std-lib SRC20 (contract PR #209):
+//   domainSeparator = keccak256(abi.encode(
+//       keccak256("EIP712Domain(string name,string version,uint256 chainId)"),
+//       keccak256("SRC20BalanceRead"), keccak256("1"), chainId))
+//   structHash = keccak256(abi.encode(
+//       keccak256("BalanceRead(address owner,uint256 expiry)"), owner, expiry))
+//   digest = keccak256(0x1901 || domainSeparator || structHash)
+// NOTE: domain is intentionally token-agnostic — no verifyingContract, no salt.
+function eip712Digest(owner: Address, expiry: bigint, chainId: bigint): Hex {
+  const domainSeparator = keccak256(
+    encodeAbiParameters(
+      [
+        { type: "bytes32" },
+        { type: "bytes32" },
+        { type: "bytes32" },
+        { type: "uint256" },
+      ],
+      [
+        keccak256(
+          toHex("EIP712Domain(string name,string version,uint256 chainId)"),
+        ),
+        keccak256(toHex("SRC20BalanceRead")),
+        keccak256(toHex("1")),
+        chainId,
+      ],
+    ),
+  );
+
+  const structHash = keccak256(
+    encodeAbiParameters(
+      [{ type: "bytes32" }, { type: "address" }, { type: "uint256" }],
+      [
+        keccak256(toHex("BalanceRead(address owner,uint256 expiry)")),
+        owner,
+        expiry,
+      ],
+    ),
+  );
+
+  return keccak256(concat(["0x1901", domainSeparator, structHash]));
+}
+
+test("signBalanceRead recovers to the owner under the EIP-712 chainId digest", async () => {
+  const signature = await signBalanceRead(PRIVATE_KEY, OWNER, EXPIRY, CHAIN_ID);
+
+  const digest = eip712Digest(OWNER, EXPIRY, CHAIN_ID);
+  const recovered = await recoverAddress({ hash: digest, signature });
+
+  expect(recovered.toLowerCase()).toBe(OWNER.toLowerCase());
+});
diff --git a/packages/batch-read-ts/src/util/signature.ts b/packages/batch-read-ts/src/util/signature.ts
index 0fb38bf..1423559 100644
--- a/packages/batch-read-ts/src/util/signature.ts
+++ b/packages/batch-read-ts/src/util/signature.ts
@@ -1,11 +1,4 @@
-import {
-  type Hex,
-  type Address,
-  keccak256,
-  encodePacked,
-  hexToSignature,
-  http,
-} from "viem";
+import { type Hex, type Address, http } from "viem";
 import { privateKeyToAccount } from "viem/accounts";
 import {
   createShieldedWalletClient,
@@ -26,34 +19,33 @@ export async function createClient(privateKey: Hex, mode: string) {
   return { client, account, chain };
 }
 
+// EIP-712 signature consumed by SRC20.balanceOfSigned (seismic-std-lib, contract PR #209).
+// The domain is deliberately token-agnostic: only { name, version, chainId } — no
+// verifyingContract and no salt, so one signature is valid across every SRC20 on the chain.
+// Adding either field changes the domain typehash and the recovered signer no longer matches.
 export async function signBalanceRead(
   privateKey: Hex,
   owner: Address,
   expiry: bigint,
+  chainId: number | bigint,
 ): Promise<Hex> {
   const account = privateKeyToAccount(privateKey);
 
-  const messageHash = keccak256(
-    encodePacked(
-      ["string", "address", "uint256"],
-      ["SRC20_BALANCE_READ", owner, expiry],
-    ),
-  );
-
-  const ethSignedHash = keccak256(
-    encodePacked(
-      ["string", "bytes32"],
-      ["\x19Ethereum Signed Message:\n32", messageHash],
-    ),
-  );
-
-  const signature = await account.sign({ hash: ethSignedHash });
-
-  const r = signature.slice(0, 66) as Hex; // First 32 bytes
-  const s = ("0x" + signature.slice(66, 130)) as Hex; // Next 32 bytes
-  const v = parseInt(signature.slice(130, 132), 16); // Last byte
-
-  return encodePacked(["bytes32", "bytes32", "uint8"], [r, s, v]);
+  return account.signTypedData({
+    domain: {
+      name: "SRC20BalanceRead",
+      version: "1",
+      chainId: Number(chainId),
+    },
+    types: {
+      BalanceRead: [
+        { name: "owner", type: "address" },
+        { name: "expiry", type: "uint256" },
+      ],
+    },
+    primaryType: "BalanceRead",
+    message: { owner, expiry },
+  });
 }
 
 export function createExpiry(hoursFromNow: number = 1): bigint {