diff --git a/contracts/interfaces/ITornadoInstance.sol b/contracts/interfaces/ITornadoInstance.sol
index b719d30..73d629c 100644
--- a/contracts/interfaces/ITornadoInstance.sol
+++ b/contracts/interfaces/ITornadoInstance.sol
@@ -3,9 +3,9 @@
 pragma solidity ^0.6.0;
 
 interface ITornadoInstance {
-  function token() external returns (address);
+  function token() external view returns (address);
 
-  function denomination() external returns (uint256);
+  function denomination() external view returns (uint256);
 
   function deposit(bytes32 commitment) external payable;
 
diff --git a/package.json b/package.json
index b10c9c0..067c28b 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "tornado-anonymity-mining",
-  "version": "2.1.0",
+  "version": "2.1.1",
   "main": "index.js",
   "repository": "https://github.com/tornadocash/tornado-anonymity-mining.git",
   "author": "Tornadocash team <hello@tornado.cash>",