diff --git a/index.js b/index.js
index 3f89ae8..f80e78e 100644
--- a/index.js
+++ b/index.js
@@ -79,6 +79,7 @@ module.exports = {
 				ignore: ['custom-properties'],
 			},
 		],
+		'lightness-notation': 'percentage',
 		'media-feature-name-no-vendor-prefix': true,
 		'media-feature-range-notation': 'context',
 		'number-max-precision': 4,