diff --git a/contracts/USDC.sol b/contracts/USDC.sol
index 786074e..7914ac5 100644
--- a/contracts/USDC.sol
+++ b/contracts/USDC.sol
@@ -5,23 +5,6 @@ import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
 import "@openzeppelin/contracts/access/AccessControl.sol";
 import "@openzeppelin/contracts/access/Ownable.sol";
 
-/**
- * @dev Interface of the zTokens to be used by Baki
- */
-interface USDCInterface {
-    /**
-     * @dev Amount of zTokens to be minted for a user
-     * requires onlyVault modifier
-     */
-    function mint(address _address, uint256 _amount) external returns (bool);
-
-    /**
-     * @dev Amount of zTokens to be burned after swap/repay functions
-     * requires onlyVault modifier
-     */
-    function burn(address _address, uint256 _amount) external returns (bool);
-}
-
 contract USDC is ERC20, AccessControl, Ownable {
 
     constructor() ERC20("USDC", "USDC") Ownable(msg.sender) {
diff --git a/contracts/Vault.sol b/contracts/Vault.sol
index 4e54ba3..bbffc2a 100644
--- a/contracts/Vault.sol
+++ b/contracts/Vault.sol
@@ -52,8 +52,6 @@ contract Vault is
 
     mapping(address => uint256) public userAccruedFeeBalance;
 
-    mapping(address => uint256) private mintersRewardPerTransaction;
-
     uint256 public globalMintersFee;
 
     address public treasuryWallet;
@@ -223,12 +221,14 @@ contract Vault is
 
         _testImpact();
 
-        collateral.transferFrom(
+        bool success = collateral.transferFrom(
             msg.sender,
             address(this),
             depositAmountInUSDC
         );
 
+        if (!success) revert();
+
         emit Deposit(msg.sender, _depositAmount, _mintAmount);
     }
 
@@ -365,11 +365,13 @@ contract Vault is
 
         uint256 amountToWithdrawInUSDC = _amountToWithdraw / USDC_DIVISOR;
 
-        collateral.transfer(
+        bool success = collateral.transfer(
             msg.sender,
             amountToWithdrawInUSDC
         );
 
+        if (!success) revert();
+
         emit Withdraw(msg.sender, _zToken, _amountToWithdraw);
     }
 
@@ -410,20 +412,22 @@ contract Vault is
 
             totalCollateral -= totalRewards;
 
-            collateral.transfer(
+            bool success = collateral.transfer(
                 msg.sender,
                 totalRewardsInUSDC
             );
+            if (!success) revert();
 
         } else {
             userCollateralBalance[_user] -= totalRewards;
 
             totalCollateral -= totalRewards;
 
-            collateral.transfer(
+            bool success = collateral.transfer(
                 msg.sender,
                 totalRewardsInUSDC
             );
+            if (!success) revert();
         }
 
         emit Liquidate(_user, userDebt, totalRewards, msg.sender);
diff --git a/contracts/usdc_faucet.sol b/contracts/usdc_faucet.sol
index 5492c8b..e3cf7e4 100644
--- a/contracts/usdc_faucet.sol
+++ b/contracts/usdc_faucet.sol
@@ -2,20 +2,7 @@
 pragma solidity 0.8.20;
 
 import "@openzeppelin/contracts/access/Ownable.sol";
-
-interface USDCInterface {
-    /**
-     * @dev Amount of zTokens to be minted for a user
-     * requires onlyVault modifier
-     */
-    function mint(address _address, uint256 _amount) external returns (bool);
-
-    /**
-     * @dev Amount of zTokens to be burned after swap/repay functions
-     * requires onlyVault modifier
-     */
-    function burn(address _address, uint256 _amount) external returns (bool);
-}
+import "./interfaces/USDCInterface.sol";
 
 contract USDCFaucet is Ownable {
     address public USDC;