diff --git a/lib/6to5/transformation/transformers/es6/constants.js b/lib/6to5/transformation/transformers/es6/constants.js
index 0d11b5fb1b..db281767dd 100644
--- a/lib/6to5/transformation/transformers/es6/constants.js
+++ b/lib/6to5/transformation/transformers/es6/constants.js
@@ -25,7 +25,7 @@ var visitor = {
         if (id === constant) continue;
 
         // check if there's been a local binding that shadows this constant
-        if (scope.bindingEquals(key, constant)) continue;
+        if (!scope.bindingEquals(key, constant)) continue;
 
         throw state.file.errorWithNode(id, key + " is read-only");
       }