diff --git a/index.js b/index.js
index 8d5ae4e..1120a27 100644
--- a/index.js
+++ b/index.js
@@ -1,4 +1,4 @@
-var valueParser = require('postcss-value-parser');
+let valueParser = require('postcss-value-parser');
 
 const PREFERS_COLOR_ONLY = /^\(\s*prefers-color-scheme\s*:\s*(dark|light)\s*\)$/
 const PREFERS_COLOR = /\(\s*prefers-color-scheme\s*:\s*(dark|light)\s*\)/g