diff --git a/eth/api.go b/eth/api.go
index c2f72a189..fb51e78c1 100644
--- a/eth/api.go
+++ b/eth/api.go
@@ -61,15 +61,6 @@ func (api *PublicEthereumAPI) Coinbase() (common.Address, error) {
 	return api.Etherbase()
 }
 
-// ChainId is the EIP-155 replay-protection chain id for the current ethereum chain config.
-func (api *PublicEthereumAPI) ChainId() (hexutil.Uint64, error) {
-	// if current block is at or past the EIP-155 replay-protection fork block, return chainID from config
-	if config := api.e.blockchain.Config(); config.IsEIP155(api.e.blockchain.CurrentBlock().Number()) {
-		return (hexutil.Uint64)(config.ChainID.Uint64()), nil
-	}
-	return hexutil.Uint64(0), fmt.Errorf("chain not synced beyond EIP-155 replay-protection fork block")
-}
-
 // PublicMinerAPI provides an API to control the miner.
 // It offers only methods that operate on data that pose no security risk when it is publicly accessible.
 type PublicMinerAPI struct {
diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go
index 622063cf6..861d42785 100644
--- a/internal/ethapi/api.go
+++ b/internal/ethapi/api.go
@@ -529,9 +529,13 @@ func NewPublicBlockChainAPI(b Backend) *PublicBlockChainAPI {
 	return &PublicBlockChainAPI{b}
 }
 
-// ChainId returns the chainID value for transaction replay protection.
-func (s *PublicBlockChainAPI) ChainId() *hexutil.Big {
-	return (*hexutil.Big)(s.b.ChainConfig().ChainID)
+// ChainId is the EIP-155 replay-protection chain id for the current ethereum chain config.
+func (api *PublicBlockChainAPI) ChainId() (*hexutil.Big, error) {
+	// if current block is at or past the EIP-155 replay-protection fork block, return chainID from config
+	if config := api.b.ChainConfig(); config.IsEIP155(api.b.CurrentBlock().Number()) {
+		return (*hexutil.Big)(config.ChainID), nil
+	}
+	return nil, fmt.Errorf("chain not synced beyond EIP-155 replay-protection fork block")
 }
 
 // BlockNumber returns the block number of the chain head.