diff --git a/src/parse.js b/src/parse.js
index 7a6d1faf0..63c66a2a5 100644
--- a/src/parse.js
+++ b/src/parse.js
@@ -300,7 +300,7 @@ function parse(source, root, options) {
 
     function parseField(parent, rule, extend) {
         var type = next();
-        if (lower(type) === "group") {
+        if (type === "group") {
             parseGroup(parent, rule);
             return;
         }