diff --git a/solidity/contracts/Oracle.sol b/solidity/contracts/Oracle.sol
index 9283cb9..67f64cd 100644
--- a/solidity/contracts/Oracle.sol
+++ b/solidity/contracts/Oracle.sol
@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.19;
 
+import {EnumerableSet} from '@openzeppelin/contracts/utils/structs/EnumerableSet.sol';
+
 import {IOracle} from '../interfaces/IOracle.sol';
 
 import {IAccessModule} from '../interfaces/modules/access/IAccessModule.sol';
@@ -15,6 +17,7 @@ import {OracleTypehash} from './utils/OracleTypehash.sol';
 
 contract Oracle is IOracle, OracleAccessController {
   using ValidatorLib for *;
+  using EnumerableSet for EnumerableSet.Bytes32Set;
 
   /// @inheritdoc IOracle
   mapping(bytes32 _requestId => uint256 _finalizedAt) public finalizedAt;
@@ -50,24 +53,13 @@ contract Oracle is IOracle, OracleAccessController {
   uint256 public totalRequestCount;
 
   /**
-   * @notice The list of the response ids for each request
+   * @notice An enumerable set of the response ids for each request
    */
-  mapping(bytes32 _requestId => bytes _responseIds) internal _responseIds;
+  mapping(bytes32 _requestId => EnumerableSet.Bytes32Set _responseIds) internal _responseIds;
 
   /// @inheritdoc IOracle
   function getResponseIds(bytes32 _requestId) public view returns (bytes32[] memory _ids) {
-    bytes memory _responses = _responseIds[_requestId];
-    uint256 _length = _responses.length / 32;
-
-    assembly {
-      for { let _i := 0 } lt(_i, _length) { _i := add(_i, 1) } {
-        // Increase the size of the array
-        mstore(_ids, add(mload(_ids), 1))
-
-        // Store the response id in the array
-        mstore(add(_ids, add(32, mul(_i, 32))), mload(add(_responses, add(32, mul(_i, 32)))))
-      }
-    }
+    _ids = _responseIds[_requestId].values();
   }
 
   /// @inheritdoc IOracle
@@ -154,7 +146,7 @@ contract Oracle is IOracle, OracleAccessController {
     }
     isParticipant[_requestId][_response.proposer] = true;
     IResponseModule(_request.responseModule).propose(_request, _response, _accessControl.user);
-    _responseIds[_requestId] = abi.encodePacked(_responseIds[_requestId], _responseId);
+    _responseIds[_requestId].add(_responseId);
     responseCreatedAt[_responseId] = block.timestamp;
 
     emit ResponseProposed(_requestId, _responseId, _response);
diff --git a/solidity/test/unit/Oracle.t.sol b/solidity/test/unit/Oracle.t.sol
index 6034398..e6c8fe0 100644
--- a/solidity/test/unit/Oracle.t.sol
+++ b/solidity/test/unit/Oracle.t.sol
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.19;
 
+import {EnumerableSet} from '@openzeppelin/contracts/utils/structs/EnumerableSet.sol';
 import 'forge-std/Test.sol';
 
 import {IModule} from '../../interfaces/IModule.sol';
@@ -71,7 +72,7 @@ contract MockOracle is Oracle {
   }
 
   function mock_addResponseId(bytes32 _requestId, bytes32 _responseId) external {
-    _responseIds[_requestId] = abi.encodePacked(_responseIds[_requestId], _responseId);
+    EnumerableSet.add(_responseIds[_requestId], _responseId);
   }
 
   function mock_setAccessModuleApproved(address _user, address _accessModule, bool _approved) external {