diff --git a/lib/6to5/transformation/transformers/es6-classes.js b/lib/6to5/transformation/transformers/es6-classes.js
index 69d3a41205..04be814120 100644
--- a/lib/6to5/transformation/transformers/es6-classes.js
+++ b/lib/6to5/transformation/transformers/es6-classes.js
@@ -14,7 +14,8 @@ exports.ClassExpression = function (node, parent, file, scope) {
       node.id = parent.key;
     }
 
-    if (t.isVariableDeclarator(parent)) {
+    if (t.isVariableDeclarator(parent) && t.isIdentifier(parent.id)) {
+      // var foo = class {};
       node.id = parent.id;
     }
   }