diff --git a/src/protocols/v4-periphery/interfaces/external/IWstETH.sol b/src/protocols/v4-periphery/interfaces/external/IWstETH.sol
new file mode 100644
index 0000000..fad3d87
--- /dev/null
+++ b/src/protocols/v4-periphery/interfaces/external/IWstETH.sol
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-3.0
+pragma solidity >=0.6.2;
+
+// SPDX-FileCopyrightText: 2021 Lido <info@lido.fi>
+// https://github.com/lidofinance/core/blob/master/contracts/0.6.12/WstETH.sol
+
+/* See contracts/COMPILERS.md */
+
+interface IWstETH {
+    function wrap(uint256 _stETHAmount) external returns (uint256);
+    function unwrap(uint256 _wstETHAmount) external returns (uint256);
+    function getStETHByWstETH(uint256 _wstETHAmount) external view returns (uint256);
+    function getWstETHByStETH(uint256 _stETHAmount) external view returns (uint256);
+    function stETH() external view returns (address);
+}