diff --git a/packages/loopring_v3/contracts/aux/agents/FastWithdrawalAgent.sol b/packages/loopring_v3/contracts/aux/agents/FastWithdrawalAgent.sol
index 5b10ba34a..dc4ff1496 100644
--- a/packages/loopring_v3/contracts/aux/agents/FastWithdrawalAgent.sol
+++ b/packages/loopring_v3/contracts/aux/agents/FastWithdrawalAgent.sol
@@ -3,6 +3,7 @@
 pragma solidity ^0.7.0;
 pragma experimental ABIEncoderV2;
 
+import "../../core/iface/IAgentRegistry.sol";
 import "../../core/iface/IExchangeV3.sol";
 import "../../lib/Claimable.sol";
 import "../../lib/EIP712.sol";
@@ -40,7 +41,7 @@ import "../../lib/SignatureUtil.sol";
 /// @author Brecht Devos - <brecht@loopring.org>
 /// @author Kongliang Zhong - <kongliang@loopring.org>
 /// @author Daniel Wang - <daniel@loopring.org>
-contract FastWithdrawalAgent is ReentrancyGuard
+contract FastWithdrawalAgent is ReentrancyGuard, IAgent
 {
     using AddressUtil       for address;
     using AddressUtil       for address payable;
diff --git a/packages/loopring_v3/contracts/core/iface/IAgentRegistry.sol b/packages/loopring_v3/contracts/core/iface/IAgentRegistry.sol
index 895825a22..c57226064 100644
--- a/packages/loopring_v3/contracts/core/iface/IAgentRegistry.sol
+++ b/packages/loopring_v3/contracts/core/iface/IAgentRegistry.sol
@@ -2,6 +2,7 @@
 // Copyright 2017 Loopring Technology Limited.
 pragma solidity ^0.7.0;
 
+interface IAgent{}
 
 interface IAgentRegistry
 {
diff --git a/packages/loopring_v3/contracts/test/AmmPool.sol b/packages/loopring_v3/contracts/test/AmmPool.sol
index 7a3ee1852..fd5988fce 100644
--- a/packages/loopring_v3/contracts/test/AmmPool.sol
+++ b/packages/loopring_v3/contracts/test/AmmPool.sol
@@ -6,6 +6,7 @@ pragma experimental ABIEncoderV2;
 import "../aux/access/IBlockReceiver.sol";
 import "../aux/transactions/TransactionReader.sol";
 import "../thirdparty/BytesUtil.sol";
+import "../core/iface/IAgentRegistry.sol";
 import "../core/iface/IExchangeV3.sol";
 import "../lib/AddressUtil.sol";
 import "../lib/ERC20.sol";
@@ -20,7 +21,7 @@ import "../core/impl/libtransactions/WithdrawTransaction.sol";
 /// @title AmmPool
 /// @author Brecht Devos - <brecht@loopring.org>
 /// @dev Incomplete AMM pool implementation for demo/testing purposes.
-contract AmmPool is IBlockReceiver {
+contract AmmPool is IBlockReceiver, IAgent {
 
     using AddressUtil       for address;
     using AddressUtil       for address payable;