diff --git a/hardhat.config.js b/hardhat.config.js
index a3b6c3dac..627b0060d 100644
--- a/hardhat.config.js
+++ b/hardhat.config.js
@@ -1,9 +1,9 @@
 const fs = require('fs');
 const path = require('path');
 
-require("@nomiclabs/hardhat-truffle5");
-require("@nomiclabs/hardhat-solhint");
-require("solidity-coverage");
+require('@nomiclabs/hardhat-truffle5');
+require('@nomiclabs/hardhat-solhint');
+require('solidity-coverage');
 
 for (const f of fs.readdirSync(path.join(__dirname, 'hardhat'))) {
   require(path.join(__dirname, 'hardhat', f));
@@ -13,14 +13,14 @@ for (const f of fs.readdirSync(path.join(__dirname, 'hardhat'))) {
  * @type import('hardhat/config').HardhatUserConfig
  */
 module.exports = {
-  solidity: "0.8.0",
+  solidity: '0.8.0',
   settings: {
     optimizer: {
       enabled: false,
       runs: 200,
     },
   },
-	networks: {
+  networks: {
     hardhat: {
       blockGasLimit: 10000000,
     },
diff --git a/test/math/SafeMath.test.js b/test/math/SafeMath.test.js
index 5613a791f..31b702a68 100644
--- a/test/math/SafeMath.test.js
+++ b/test/math/SafeMath.test.js
@@ -26,7 +26,7 @@ contract('SafeMath', function (accounts) {
   }
 
   async function testFailsCommutative (fn, lhs, rhs, reason, ...extra) {
-    if (reason == undefined) {
+    if (reason === undefined) {
       await expectRevert.unspecified(fn(lhs, rhs, ...extra));
       await expectRevert.unspecified(fn(rhs, lhs, ...extra));
     } else {
diff --git a/test/proxy/UpgradeableProxy.behaviour.js b/test/proxy/UpgradeableProxy.behaviour.js
index 3a73d65c7..dc6ffb1fb 100644
--- a/test/proxy/UpgradeableProxy.behaviour.js
+++ b/test/proxy/UpgradeableProxy.behaviour.js
@@ -5,10 +5,6 @@ const { expect } = require('chai');
 
 const DummyImplementation = artifacts.require('DummyImplementation');
 
-function toChecksumAddress (address) {
-  return ethereumjsUtil.toChecksumAddress('0x' + address.replace(/^0x/, '').padStart(40, '0').substr(-40));
-}
-
 const IMPLEMENTATION_LABEL = 'eip1967.proxy.implementation';
 
 function toChecksumAddress (address) {