diff --git a/modules/@angular/common/src/directives/observable_list_diff.ts b/modules/@angular/common/src/directives/observable_list_diff.ts
index cbc7df8772..9a1f1cfc4b 100644
--- a/modules/@angular/common/src/directives/observable_list_diff.ts
+++ b/modules/@angular/common/src/directives/observable_list_diff.ts
@@ -6,5 +6,6 @@ import {} from '../../src/facade/lang';
 /**
  * This module exists in Dart, but not in Typescript. This exported symbol
  * is only here to help Typescript think this is a module.
+ * @internal
  */
 export var workaround_empty_observable_list_diff: any;