diff --git a/CHANGELOG.md b/CHANGELOG.md
index d60760cf1e..b2a83446aa 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,17 @@ Documentation of all notable changes to the **evmone** project.
 The format is based on [Keep a Changelog],
 and this project adheres to [Semantic Versioning].
 
+
+## [0.3.0] - unreleased
+
+### Added
+
+- **Istanbul** EVM revision support with new costs for some instructions ([EIP-1884]).
+  [#191](https://github.com/ethereum/evmone/pull/191)
+- Implementation of CHAINID instruction from the **Istanbul** EVM revision ([EIP-1344]).
+  [#190](https://github.com/ethereum/evmone/pull/190)
+
+
 ## [0.2.0] - 2019-09-24
 
 This release of evmone is binary compatible with 0.1 and delivers big performance improvements
@@ -106,11 +117,14 @@ It delivers fully-compatible and high-speed EVM implementation.
 - The [intx 0.2.0](https://github.com/chfast/intx/releases/tag/v0.2.0) library is used for 256-bit precision arithmetic. 
 
 
+[0.3.0]: https://github.com/ethereum/evmone/compare/v0.2.0..master
 [0.2.0]: https://github.com/ethereum/evmone/releases/tag/v0.2.0
 [0.1.1]: https://github.com/ethereum/evmone/releases/tag/v0.1.1
 [0.1.0]: https://github.com/ethereum/evmone/releases/tag/v0.1.0
 
 [Aleth]: https://github.com/ethereum/aleth
+[EIP-1884]: https://eips.ethereum.org/EIPS/eip-1884
+[EIP-1344]: https://eips.ethereum.org/EIPS/eip-1344
 [EVMC]: https://github.com/ethereum/evmc
 [intx]: https://github.com/chfast/intx
 [Keep a Changelog]: https://keepachangelog.com/en/1.0.0/
diff --git a/lib/evmone/instructions.cpp b/lib/evmone/instructions.cpp
index 5a33b1dec8..3e90958ac9 100644
--- a/lib/evmone/instructions.cpp
+++ b/lib/evmone/instructions.cpp
@@ -330,6 +330,12 @@ const instruction* op_balance(const instruction* instr, execution_state& state)
     return ++instr;
 }
 
+const instruction* op_chainid(const instruction* instr, execution_state& state) noexcept
+{
+    state.stack.push(intx::be::load<uint256>(state.host.get_tx_context().chain_id));
+    return ++instr;
+}
+
 const instruction* op_origin(const instruction* instr, execution_state& state) noexcept
 {
     state.stack.push(intx::be::load<uint256>(state.host.get_tx_context().tx_origin));
@@ -1378,7 +1384,7 @@ constexpr op_table create_op_table_istanbul() noexcept
 {
     auto table = create_op_table_constantinople();
     table[OP_BALANCE] = {op_balance, 700, 1, 0};
-    table[OP_CHAINID] = {op_undefined, 2, 0, 1};
+    table[OP_CHAINID] = {op_chainid, 2, 0, 1};
     table[OP_EXTCODEHASH] = {op_extcodehash, 700, 1, 0};
     table[OP_SELFBALANCE] = {op_undefined, 5, 0, 1};
     table[OP_SLOAD] = {op_sload, 800, 1, 0};
diff --git a/test/unittests/evm_state_test.cpp b/test/unittests/evm_state_test.cpp
index 86e9f08897..579072eb2e 100644
--- a/test/unittests/evm_state_test.cpp
+++ b/test/unittests/evm_state_test.cpp
@@ -171,26 +171,28 @@ TEST_F(evm_state, sstore_cost)
 
 TEST_F(evm_state, tx_context)
 {
+    rev = EVMC_ISTANBUL;
+
     host.tx_context.block_timestamp = 0xdd;
-    host.tx_context.block_coinbase.bytes[1] = 0xcc;
     host.tx_context.block_number = 0x1100;
-    host.tx_context.block_difficulty.bytes[1] = 0xdd;
     host.tx_context.block_gas_limit = 0x990000;
-    host.tx_context.tx_gas_price.bytes[2] = 0x66;
+    host.tx_context.chain_id.bytes[28] = 0xaa;
+    host.tx_context.block_coinbase.bytes[1] = 0xcc;
     host.tx_context.tx_origin.bytes[2] = 0x55;
+    host.tx_context.block_difficulty.bytes[1] = 0xdd;
+    host.tx_context.tx_gas_price.bytes[2] = 0x66;
 
-    std::string s;
-    s += "4241173a17";        // TIMESTAMP COINBASE OR GASPRICE OR
-    s += "4317441745173217";  // NUMBER OR DIFFICULTY OR GASLIMIT OR ORIGIN OR
-    s += "600052";            // m[0..] =
-    s += "60206000f3";        // RETURN(0,32)
-    execute(47, s);
+    auto const code = bytecode{} + OP_TIMESTAMP + OP_COINBASE + OP_OR + OP_GASPRICE + OP_OR +
+                      OP_NUMBER + OP_OR + OP_DIFFICULTY + OP_OR + OP_GASLIMIT + OP_OR + OP_ORIGIN +
+                      OP_OR + OP_CHAINID + OP_OR + ret_top();
+    execute(52, code);
     EXPECT_EQ(result.status_code, EVMC_SUCCESS);
     EXPECT_EQ(result.gas_left, 0);
     ASSERT_EQ(result.output_size, 32);
     EXPECT_EQ(result.output_data[31], 0xdd);
     EXPECT_EQ(result.output_data[30], 0x11);
     EXPECT_EQ(result.output_data[29], 0x99);
+    EXPECT_EQ(result.output_data[28], 0xaa);
     EXPECT_EQ(result.output_data[14], 0x55);
     EXPECT_EQ(result.output_data[13], 0xcc);
     EXPECT_EQ(result.output_data[2], 0x66);