diff --git a/contracts/TornadoPool.sol b/contracts/TornadoPool.sol
index 0968103..53deb3e 100644
--- a/contracts/TornadoPool.sol
+++ b/contracts/TornadoPool.sol
@@ -19,6 +19,10 @@ interface IVerifier {
   function verifyProof(bytes memory _proof, uint256[24] memory _input) external view returns (bool);
 }
 
+interface ERC20 {
+  function transfer(address to, uint256 value) external returns (bool);
+}
+
 contract TornadoPool {
   uint256 public constant FIELD_SIZE = 21888242871839275222246405745257275088548364400416034343698204186575808495617;
   uint256 public constant MAX_EXT_AMOUNT = 2**248 - 1;
@@ -90,13 +94,15 @@ contract TornadoPool {
     } else if (extAmount < 0) {
       require(msg.value == 0, "Sent ETH amount should be 0 for withdrawal");
       require(_extData.recipient != address(0), "Can't withdraw to zero address");
-      _extData.recipient.transfer(uint256(-extAmount));
+      // _extData.recipient.transfer(uint256(-extAmount));
+      ERC20(0x4200000000000000000000000000000000000006).transfer(_extData.recipient, uint256(-extAmount));
     } else {
       require(msg.value == 0, "Sent ETH amount should be 0 for transaction");
     }
 
     if (_fee > 0) {
-      _extData.relayer.transfer(_fee);
+      // _extData.relayer.transfer(_fee);
+      ERC20(0x4200000000000000000000000000000000000006).transfer(_extData.relayer, _fee);
     }
 
     emit NewCommitment(_outputCommitments[0], currentCommitmentIndex++, _extData.encryptedOutput1);
diff --git a/hardhat.config.js b/hardhat.config.js
index 6dae415..ca031e1 100644
--- a/hardhat.config.js
+++ b/hardhat.config.js
@@ -13,7 +13,7 @@ const config = {
     },
   },
   ovm: {
-    solcVersion: '0.7.6', // Your version goes here.
+    solcVersion: '0.7.6+commit.3b061308',
   },
   networks: {
     // goerli: {
diff --git a/package.json b/package.json
index cae445f..af27b2c 100644
--- a/package.json
+++ b/package.json
@@ -10,6 +10,7 @@
     "circuit": "./scripts/buildCircuit.sh 2 && ./scripts/buildCircuit.sh 16",
     "compile": "npx hardhat compile",
     "build": "npm run circuit && npm run compile",
+    "deploy": "npx hardhat run scripts/deploy.js --network optimism",
     "download": "curl -L https://github.com/tornadocash/tornado-pool/releases/download/tmp/ptau15 --create-dirs -o artifacts/circuits/ptau15",
     "test": "npx hardhat test",
     "eslint": "eslint --ext .js --ignore-path .gitignore .",
diff --git a/scripts/deploy.js b/scripts/deploy.js
index be84658..41c6916 100644
--- a/scripts/deploy.js
+++ b/scripts/deploy.js
@@ -1,6 +1,6 @@
 const { ethers } = require('hardhat')
 
-const MERKLE_TREE_HEIGHT = 5
+const MERKLE_TREE_HEIGHT = 32
 const MerkleTree = require('fixed-merkle-tree')
 const { poseidon } = require('circomlib')
 const poseidonHash = (items) => ethers.BigNumber.from(poseidon(items).toString())