diff --git a/rpc/src/v1/impls/eth.rs b/rpc/src/v1/impls/eth.rs
index d912c13dd..548271f89 100644
--- a/rpc/src/v1/impls/eth.rs
+++ b/rpc/src/v1/impls/eth.rs
@@ -48,6 +48,7 @@ use v1::types::{
 	RichBlock, Block, BlockTransactions, BlockNumber, Bytes, SyncStatus, SyncInfo,
 	Transaction, CallRequest, Index, Filter, Log, Receipt, Work,
 	H64 as RpcH64, H256 as RpcH256, H160 as RpcH160, U256 as RpcU256, block_number_to_id,
+	U64 as RpcU64,
 };
 use v1::metadata::Metadata;
 
@@ -513,6 +514,10 @@ impl<C, SN: ?Sized, S: ?Sized, M, EM, T: StateInfo + 'static> Eth for EthClient<
 		Ok(self.miner.is_currently_sealing())
 	}
 
+	fn chain_id(&self) -> Result<Option<RpcU64>> {
+		Ok(self.client.signing_chain_id().map(RpcU64::from))
+	}
+
 	fn hashrate(&self) -> Result<RpcU256> {
 		Ok(RpcU256::from(self.external_miner.hashrate()))
 	}
diff --git a/rpc/src/v1/impls/light/eth.rs b/rpc/src/v1/impls/light/eth.rs
index 34b89ac9f..2a2563016 100644
--- a/rpc/src/v1/impls/light/eth.rs
+++ b/rpc/src/v1/impls/light/eth.rs
@@ -49,6 +49,7 @@ use v1::types::{
 	RichBlock, Block, BlockTransactions, BlockNumber, LightBlockNumber, Bytes, SyncStatus, SyncInfo,
 	Transaction, CallRequest, Index, Filter, Log, Receipt, Work,
 	H64 as RpcH64, H256 as RpcH256, H160 as RpcH160, U256 as RpcU256,
+	U64 as RpcU64,
 };
 use v1::metadata::Metadata;
 
@@ -246,6 +247,10 @@ impl<T: LightChainClient + 'static> Eth for EthClient<T> {
 		Ok(false)
 	}
 
+	fn chain_id(&self) -> Result<Option<RpcU64>> {
+		Ok(self.client.signing_chain_id().map(RpcU64::from))
+	}
+
 	fn hashrate(&self) -> Result<RpcU256> {
 		Ok(Default::default())
 	}
diff --git a/rpc/src/v1/impls/light/parity.rs b/rpc/src/v1/impls/light/parity.rs
index 3f51826fc..18577926c 100644
--- a/rpc/src/v1/impls/light/parity.rs
+++ b/rpc/src/v1/impls/light/parity.rs
@@ -38,7 +38,7 @@ use v1::helpers::light_fetch::LightFetch;
 use v1::metadata::Metadata;
 use v1::traits::Parity;
 use v1::types::{
-	Bytes, U256, U64, H64, H160, H256, H512, CallRequest,
+	Bytes, U256, H64, H160, H256, H512, CallRequest,
 	Peers, Transaction, RpcSettings, Histogram,
 	TransactionStats, LocalTransactionStatus,
 	BlockNumber, LightBlockNumber, ConsensusCapability, VersionInfo,
@@ -328,10 +328,6 @@ impl Parity for ParityClient {
 		Err(errors::light_unimplemented(None))
 	}
 
-	fn chain_id(&self) -> Result<Option<U64>> {
-		Ok(self.client.signing_chain_id().map(U64::from))
-	}
-
 	fn chain(&self) -> Result<String> {
 		Ok(self.settings.chain.clone())
 	}
diff --git a/rpc/src/v1/impls/parity.rs b/rpc/src/v1/impls/parity.rs
index 3dce93ecd..a003b3c11 100644
--- a/rpc/src/v1/impls/parity.rs
+++ b/rpc/src/v1/impls/parity.rs
@@ -40,7 +40,7 @@ use v1::helpers::{self, errors, fake_sign, ipfs, SigningQueue, SignerService, Ne
 use v1::metadata::Metadata;
 use v1::traits::Parity;
 use v1::types::{
-	Bytes, U256, U64, H64, H160, H256, H512, CallRequest,
+	Bytes, U256, H64, H160, H256, H512, CallRequest,
 	Peers, Transaction, RpcSettings, Histogram,
 	TransactionStats, LocalTransactionStatus,
 	BlockNumber, ConsensusCapability, VersionInfo,
@@ -173,10 +173,6 @@ impl<C, M, U, S> Parity for ParityClient<C, M, U> where
 		Ok(self.settings.chain.clone())
 	}
 
-	fn chain_id(&self) -> Result<Option<U64>> {
-		Ok(self.client.signing_chain_id().map(U64::from))
-	}
-
 	fn chain(&self) -> Result<String> {
 		Ok(self.client.spec_name())
 	}
diff --git a/rpc/src/v1/tests/mocked/eth.rs b/rpc/src/v1/tests/mocked/eth.rs
index ff364cf7f..040bf4be6 100644
--- a/rpc/src/v1/tests/mocked/eth.rs
+++ b/rpc/src/v1/tests/mocked/eth.rs
@@ -178,6 +178,15 @@ fn rpc_eth_syncing() {
 	assert_eq!(tester.io.handle_request_sync(request), Some(false_res.to_owned()));
 }
 
+#[test]
+fn rpc_eth_chain_id() {
+	let tester = EthTester::default();
+	let request = r#"{"jsonrpc": "2.0", "method": "eth_chainId", "params": [], "id": 1}"#;
+	let response = r#"{"jsonrpc":"2.0","result":null,"id":1}"#;
+
+	assert_eq!(tester.io.handle_request_sync(request), Some(response.to_owned()));
+}
+
 #[test]
 fn rpc_eth_hashrate() {
 	let tester = EthTester::default();
diff --git a/rpc/src/v1/tests/mocked/parity.rs b/rpc/src/v1/tests/mocked/parity.rs
index 8ac8e44eb..0b59e5beb 100644
--- a/rpc/src/v1/tests/mocked/parity.rs
+++ b/rpc/src/v1/tests/mocked/parity.rs
@@ -193,17 +193,6 @@ fn rpc_parity_extra_data() {
 	assert_eq!(io.handle_request_sync(request), Some(response.to_owned()));
 }
 
-#[test]
-fn rpc_parity_chain_id() {
-	let deps = Dependencies::new();
-	let io = deps.default_client();
-
-	let request = r#"{"jsonrpc": "2.0", "method": "parity_chainId", "params": [], "id": 1}"#;
-	let response = r#"{"jsonrpc":"2.0","result":null,"id":1}"#;
-
-	assert_eq!(io.handle_request_sync(request), Some(response.to_owned()));
-}
-
 #[test]
 fn rpc_parity_default_extra_data() {
 	use version::version_data;
diff --git a/rpc/src/v1/traits/eth.rs b/rpc/src/v1/traits/eth.rs
index a11b86806..0c0041bb7 100644
--- a/rpc/src/v1/traits/eth.rs
+++ b/rpc/src/v1/traits/eth.rs
@@ -20,7 +20,7 @@ use jsonrpc_macros::Trailing;
 
 use v1::types::{RichBlock, BlockNumber, Bytes, CallRequest, Filter, FilterChanges, Index};
 use v1::types::{Log, Receipt, SyncStatus, Transaction, Work};
-use v1::types::{H64, H160, H256, U256};
+use v1::types::{H64, H160, H256, U256, U64};
 
 build_rpc_trait! {
 	/// Eth rpc interface.
@@ -47,6 +47,12 @@ build_rpc_trait! {
 		#[rpc(name = "eth_mining")]
 		fn is_mining(&self) -> Result<bool>;
 
+		/// Returns the chain ID used for transaction signing at the
+		/// current best block. None is returned if not
+		/// available.
+		#[rpc(name = "eth_chainId")]
+		fn chain_id(&self) -> Result<Option<U64>>;
+
 		/// Returns current gas_price.
 		#[rpc(name = "eth_gasPrice")]
 		fn gas_price(&self) -> Result<U256>;
diff --git a/rpc/src/v1/traits/parity.rs b/rpc/src/v1/traits/parity.rs
index 0dc0f15dc..a14369581 100644
--- a/rpc/src/v1/traits/parity.rs
+++ b/rpc/src/v1/traits/parity.rs
@@ -22,7 +22,7 @@ use jsonrpc_core::{BoxFuture, Result};
 use jsonrpc_macros::Trailing;
 
 use v1::types::{
-	H64, H160, H256, H512, U256, U64, Bytes, CallRequest,
+	H64, H160, H256, H512, U256, Bytes, CallRequest,
 	Peers, Transaction, RpcSettings, Histogram,
 	TransactionStats, LocalTransactionStatus,
 	BlockNumber, ConsensusCapability, VersionInfo,
@@ -172,12 +172,6 @@ build_rpc_trait! {
 		#[rpc(name = "parity_mode")]
 		fn mode(&self) -> Result<String>;
 
-		/// Returns the chain ID used for transaction signing at the
-		/// current best block. None is returned if not
-		/// available.
-		#[rpc(name = "parity_chainId")]
-		fn chain_id(&self) -> Result<Option<U64>>;
-
 		/// Get the chain name. Returns one of the pre-configured chain names or a filename.
 		#[rpc(name = "parity_chain")]
 		fn chain(&self) -> Result<String>;