diff --git a/lib/lexer.js b/lib/lexer.js
index 220fc78..4b8e583 100644
--- a/lib/lexer.js
+++ b/lib/lexer.js
@@ -450,6 +450,7 @@ function lex(css) {
           if ('at-group' === getState(1)) {
             initializeToken('at-group-end');
             addToken();
+            // If we're at 'at-group', pop to prior 'before-selector'
             popState();
           }
         }