diff --git a/lib/rules/no-empty-source/index.js b/lib/rules/no-empty-source/index.js
index <HASH>..<HASH> 100644
--- a/lib/rules/no-empty-source/index.js
+++ b/lib/rules/no-empty-source/index.js
@@ -17,7 +17,7 @@ const rule = function(actual) {
       return;
     }
 
-    if (!/^\s*$/.test(root.toString())) {
+    if (!/^\s*$/.test(root.source.input.css)) {
       return;
     }
`no-empty-source` compatible with processor (#<I>)