diff --git a/contracts/contracts/paymasters/PrivateMerklePaymaster.sol b/contracts/contracts/paymasters/PrivateMerklePaymaster.sol
index 5e9724a..73d94a6 100644
--- a/contracts/contracts/paymasters/PrivateMerklePaymaster.sol
+++ b/contracts/contracts/paymasters/PrivateMerklePaymaster.sol
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.18;
 
+import { MerkleTreeWithHistory } from "./MerkleTreeWithHistory.sol";
 import { ReentrancyGuard } from "@openzeppelin/contracts/security/ReentrancyGuard.sol";
 
 abstract contract PrivateMerklePaymaster is MerkleTreeWithHistory, ReentrancyGuard {