diff --git a/contracts/SwapKiwi.sol b/contracts/SwapKiwi.sol
index 3dcd649..37464ff 100644
--- a/contracts/SwapKiwi.sol
+++ b/contracts/SwapKiwi.sol
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: GPL-3.0
+
 pragma solidity ^0.8.1;
 
 import "@openzeppelin/contracts/token/ERC721/IERC721Receiver.sol";