diff --git a/lib/6to5/generation/generator.js b/lib/6to5/generation/generator.js
index bf7a57223c..18fa9b00a3 100644
--- a/lib/6to5/generation/generator.js
+++ b/lib/6to5/generation/generator.js
@@ -161,7 +161,7 @@ CodeGenerator.prototype.print = function (node, parent, opts) {
 
     this.printTrailingComments(node, parent);
   } else {
-    throw new ReferenceError("unknown node " + node.type + " " + JSON.stringify(node));
+    throw new ReferenceError("unknown node " + node.type);
   }
 };