diff --git a/contracts/src/token/erc20/utils/safe_erc20.rs b/contracts/src/token/erc20/utils/safe_erc20.rs
index e5b48616..b242c0d0 100644
--- a/contracts/src/token/erc20/utils/safe_erc20.rs
+++ b/contracts/src/token/erc20/utils/safe_erc20.rs
@@ -36,7 +36,7 @@ sol_interface! {
         /// Moves a `value` amount of tokens from the caller's account to `to`.
         /// Returns a boolean value indicating whether the operation succeeded.
         /// Emits a {Transfer} event.
-        function transfer(address to, uint256 value) external returns (bytes4);
+        function transfer(address to, uint256 amount) external returns (bool);
     }
 }
 
@@ -72,7 +72,7 @@ impl SafeErc20 {
 
         match erc20.transfer(call, to, value) {
             Ok(data) => {
-                if data.is_empty() && !Address::has_code(&token) {
+                if data && !Address::has_code(&token) {
                     return Err(Error::SafeErc20FailedOperation(
                         SafeErc20FailedOperation { token },
                     ));
diff --git a/examples/safe-erc20/src/ERC20Mock.sol b/examples/safe-erc20/src/ERC20Mock.sol
index 5f7499a3..96370d15 100644
--- a/examples/safe-erc20/src/ERC20Mock.sol
+++ b/examples/safe-erc20/src/ERC20Mock.sol
@@ -2,20 +2,20 @@
 
 pragma solidity ^0.8.21;
 
-import "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/v5.0.2/contracts/token/ERC20/ERC20.sol";
+contract ERC20Mock {
+    mapping(address => uint256) private _balances;
 
-contract ERC20Mock is ERC20 {
-    constructor() ERC20("MyToken", "MTK") {}
-
-    function balanceOf(address account) public override view returns (uint256) {
-        return super.balanceOf(account);
+    function balanceOf(address account) public view returns (uint256) {
+        return _balances[account];
     }
 
     function mint(address account, uint256 amount) public {
-        super._mint(account, amount);
+        _balances[account] += amount;
     }
 
-    function transfer(address to, uint256 amount) public override returns (bool) {
-        return super.transfer(to, amount);
+    function transfer(address to, uint256 amount) public returns (bool) {
+        _balances[msg.sender] -= amount;
+        _balances[to] += amount;
+        return true;
     }
 }
\ No newline at end of file
diff --git a/examples/safe-erc20/tests/mock/erc20.rs b/examples/safe-erc20/tests/mock/erc20.rs
index f51f3880..3a13124f 100644
--- a/examples/safe-erc20/tests/mock/erc20.rs
+++ b/examples/safe-erc20/tests/mock/erc20.rs
@@ -6,20 +6,22 @@ use e2e::Wallet;
 sol! {
     #[allow(missing_docs)]
     // Built with Remix IDE; solc v0.8.21+commit.d9974bed
-    #[sol(rpc, bytecode="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")]
-    contract ERC20Mock is ERC20 {
-        constructor() ERC20("MyToken", "MTK") {}
+    #[sol(rpc, bytecode="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")]
+    contract ERC20Mock {
+        mapping(address => uint256) private _balances;
 
-        function balanceOf(address account) public override view returns (uint256) {
-            return super.balanceOf(account);
+        function balanceOf(address account) public view returns (uint256) {
+            return _balances[account];
         }
 
         function mint(address account, uint256 amount) public {
-            super._mint(account, amount);
+            _balances[account] += amount;
         }
 
-        function transfer(address to, uint256 amount) public override returns (bool) {
-            return super.transfer(to, amount);
+        function transfer(address to, uint256 amount) public returns (bool) {
+            _balances[msg.sender] -= amount;
+            _balances[to] += amount;
+            return true;
         }
     }
 }
diff --git a/examples/safe-erc20/tests/safe-erc20.rs b/examples/safe-erc20/tests/safe-erc20.rs
index 77bb60a7..38dfd01b 100644
--- a/examples/safe-erc20/tests/safe-erc20.rs
+++ b/examples/safe-erc20/tests/safe-erc20.rs
@@ -40,8 +40,8 @@ async fn safe_transfers(alice: Account, bob: Account) -> eyre::Result<()> {
     let ERC20Mock::balanceOfReturn { _0: bob_balance } =
         erc20_alice.balanceOf(bob_addr).call().await?;
 
-    assert_eq!(initial_alice_balance - value, alice_balance);
     assert_eq!(initial_bob_balance + value, bob_balance);
+    assert_eq!(initial_alice_balance - value, alice_balance);
 
     Ok(())
 }