diff --git a/src/lib/es6.d.ts b/src/lib/es6.d.ts
index 531dbf9e5ea..c5dbeb65749 100644
--- a/src/lib/es6.d.ts
+++ b/src/lib/es6.d.ts
@@ -565,7 +565,7 @@ interface IterableIterator<T> extends Iterator<T> {
 }
 
 interface GeneratorFunction extends Function {
-
+    [Symbol.toStringTag]: string;
 }
 
 interface GeneratorFunctionConstructor {