diff --git a/src/components/AgentManage.tsx b/src/components/AgentManage.tsx
index cdb1cec6..0385a71a 100644
--- a/src/components/AgentManage.tsx
+++ b/src/components/AgentManage.tsx
@@ -21,7 +21,7 @@ const LLM_MODELS = [
 const EIP712_DOMAIN = {
   name: "ERC8004IdentityRegistry",
   version: "1",
-  chainId: BigInt(BASE_CHAIN_ID),
+  chainId: Number(BASE_CHAIN_ID),
   verifyingContract: ERC8004_REGISTRY,
 } as const;
 
diff --git a/src/components/AgentRegister.tsx b/src/components/AgentRegister.tsx
index ba1101d3..1d093410 100644
--- a/src/components/AgentRegister.tsx
+++ b/src/components/AgentRegister.tsx
@@ -23,7 +23,7 @@ type WizardStep = 1 | 2 | "3a" | "3b" | "3c" | "done";
 const EIP712_DOMAIN = {
   name: "ERC8004IdentityRegistry",
   version: "1",
-  chainId: BigInt(BASE_CHAIN_ID),
+  chainId: Number(BASE_CHAIN_ID),
   verifyingContract: ERC8004_REGISTRY,
 } as const;