diff --git a/index.js b/index.js
index 4cad6ca..e2d9fa4 100644
--- a/index.js
+++ b/index.js
@@ -69,6 +69,12 @@ module.exports = {
 		'no-unreachable-loop': 'error',
 		'no-unsafe-finally': 'error',
 		'no-unsafe-negation': 'error',
+		'no-unsafe-optional-chaining': [
+			'error',
+			{
+				disallowArithmeticOperators: true
+			}
+		],
 		'no-useless-backreference': 'error',
 		'use-isnan': 'error',
 		'valid-typeof': [
diff --git a/package.json b/package.json
index ed51460..9df70a8 100644
--- a/package.json
+++ b/package.json
@@ -51,15 +51,15 @@
 		"simple"
 	],
 	"dependencies": {
-		"confusing-browser-globals": "1.0.9"
+		"confusing-browser-globals": "1.0.10"
 	},
 	"devDependencies": {
 		"ava": "^2.4.0",
-		"eslint": "^7.14.0",
+		"eslint": "^7.17.0",
 		"is-plain-obj": "^3.0.0",
 		"temp-write": "^4.0.0"
 	},
 	"peerDependencies": {
-		"eslint": ">=7.14.0"
+		"eslint": ">=7.17.0"
 	}
 }