diff --git a/readme.md b/readme.md
index afe36bf..83842cc 100644
--- a/readme.md
+++ b/readme.md
@@ -32,7 +32,7 @@ Additional methods other than NEP-5 methods used to support GAS-CGAS swap:
 | getRefundTarget    | byte[] txId                        | byte[]                                      | Get the owner of the UTXO pending refund; the parameter is the TxId of the UTXO (confirm that a UTXO consists of TxId and output index; the output index takes the default value of 0); the return value is the account the UTXO is refunded to, whose owner can set the UTXO as a transaction input and send GAS from the CGAS address to his/her account. |
 | getTxInfo          | byte[] txId                        | [TransferInfo](NeoContract/TransferInfo.cs) | Get detailed transfer info under a TxId. TxInfo will be recorded under the following 4 instructions: mintTokens, refund, transfer, transferAPP. |
 | mintTokens         |                                    | bool                                        | A mintTokens method for CGAS users, who can transfer GAS to CGAS contract address by constructing InvocationTransaction and convert GAS to CGAS by invoking mintTokens method. Upon successful  invocation, CGAS in the equal value of the GAS will be added to the user's asset account. |
-| refund             | byte[] from                        | bool                                        | It takes two steps to claim CGAS and convert it to GAS. First, construct an InvocationTransaction, including  GAS transfer from the CGAS address to the CGAS address (the transfer amount should be the GAS amount users expect to get refunded) and the invocation of refund method (set the parameter as the Script Hash of the refund account). Upon successful invocation, CGAS in the equal amount of the refunded GAS will be automatically destroyed and the No.0 output of the transaction will be marked with the ownership of the user. Second, the user may construct a transaction and set the UTXO marked in the first step as a transaction input and his/her account as the transaction output to get GAS from the CGAS address. |
+| refund             | byte[] from                        | bool                                        | It takes two steps to claim CGAS and convert it to GAS. First, construct an InvocationTransaction, including GAS transfer within the same CGAS address (the transfer amount should be the GAS amount users expect to get refunded) to invoke the refund method (set the parameter as the Script Hash of the refund account). Upon successful invocation, CGAS in the equal amount of the refunded GAS will be automatically destroyed and the No.0 output of the transaction will be marked with the ownership of the user. Second, the user may construct a transaction and set the UTXO marked in the first step as a transaction input and his/her account as the transaction output to get GAS from the CGAS address. |
 | transferAPP        | byte[] from, byte[] to, int amount | bool                                        | Transfer by contract call; parameter setting can be referred to the transfer method. |
 | supportedStandards |                                    | string                                      | NEP-10 standard for return contract; the return value is constant "{\"NEP-5\", \"NEP-7\", \"NEP-10\"}". |