diff --git a/packages/upgrade/src/common/downgrade_injectable.ts b/packages/upgrade/src/common/downgrade_injectable.ts
index 7a1a50f054b37..e9894e36fb7f7 100644
--- a/packages/upgrade/src/common/downgrade_injectable.ts
+++ b/packages/upgrade/src/common/downgrade_injectable.ts
@@ -53,7 +53,7 @@ import {INJECTOR_KEY} from './constants';
  */
 export function downgradeInjectable(token: any): Function {
   const factory = function(i: Injector) { return i.get(token); };
-  (factory as any).$inject = [INJECTOR_KEY];
+  (factory as any)['$inject'] = [INJECTOR_KEY];
 
   return factory;
 }