diff --git a/README.md b/README.md
index 5248f7f..493bb77 100644
--- a/README.md
+++ b/README.md
@@ -28,9 +28,7 @@ const txParams = {
   gasLimit: '0x2710',
   to: '0x0000000000000000000000000000000000000000',
   value: '0x00',
-  data: '0x7f7465737432000000000000000000000000000000000000000000000000000000600057',
-  // EIP 155 chainId - mainnet: 1, ropsten: 3
-  chainId: 3,
+  data: '0x7f7465737432000000000000000000000000000000000000000000000000000000600057'
 }
 
 const tx = new EthereumTx(txParams)