diff --git a/contract/SimpleLending.sol b/contract/SimpleLending.sol
index 8b1f3ef..729a6db 100644
--- a/contract/SimpleLending.sol
+++ b/contract/SimpleLending.sol
@@ -1,11 +1,7 @@
 pragma solidity 0.5.10;
 
 interface ERC20Interface {
-    function totalSupply() external view returns (uint);
-    function balanceOf(address tokenOwner) external view returns (uint balance);
-    function allowance(address tokenOwner, address spender) external view returns (uint remaining);
     function transfer(address to, uint tokens) external returns (bool success);
-    function approve(address spender, uint tokens) external returns (bool success);
     function transferFrom(address from, address to, uint tokens) external returns (bool success);
 }