diff --git a/lib/6to5/transformation/transformers/es6-generators/runtime.js b/lib/6to5/transformation/transformers/es6-generators/runtime.js
index 2adc60afdd..0c8f932f1f 100644
--- a/lib/6to5/transformation/transformers/es6-generators/runtime.js
+++ b/lib/6to5/transformation/transformers/es6-generators/runtime.js
@@ -27,20 +27,14 @@ var ContinueSentinel = {};
 
 // Dummy constructor that we use as the .constructor property for
 // functions that return Generator objects.
-var GF = function GeneratorFunction() {};
+function GeneratorFunction() {}
 var GFp = function GeneratorFunctionPrototype() {};
 var Gp = GFp.prototype = Generator.prototype;
-(GFp.constructor = GF).prototype =
-  Gp.constructor = GFp;
-
-// Ensure isGeneratorFunction works when Function#name not supported.
-var GFName = "GeneratorFunction";
-if (GF.name !== GFName) GF.name = GFName;
-if (GF.name !== GFName) throw new Error(GFName + " renamed?");
+(GFp.constructor = GeneratorFunction).prototype = Gp.constructor = GFp;
 
 runtime.isGeneratorFunction = function (genFun) {
   var ctor = genFun && genFun.constructor;
-  return ctor ? GF.name === ctor.name : false;
+  return ctor ? GeneratorFunction.name === ctor.name : false;
 };
 
 runtime.mark = function (genFun) {