diff --git a/packages/ember-data/lib/initializers/store.js b/packages/ember-data/lib/initializers/store.js
index cfe36b195dc..58c3eaf0d21 100644
--- a/packages/ember-data/lib/initializers/store.js
+++ b/packages/ember-data/lib/initializers/store.js
@@ -34,8 +34,8 @@ export default function initializeStore(registry, application) {
   ]);
 
   // new go forward paths
-  registry.register('serializer:-default', JSONSerializer);
-  registry.register('serializer:-rest', RESTSerializer);
+  registry.register('serializer:-default', JSONSerializer.extend({ isNewSerializerAPI: true }));
+  registry.register('serializer:-rest', RESTSerializer.extend({ isNewSerializerAPI: true }));
   registry.register('adapter:-rest', RESTAdapter);
 
   registry.register('adapter:-json-api', JSONAPIAdapter);
diff --git a/packages/ember-data/lib/system/store/container-instance-cache.js b/packages/ember-data/lib/system/store/container-instance-cache.js
index 5fbb9c90be6..94d19ba85c7 100644
--- a/packages/ember-data/lib/system/store/container-instance-cache.js
+++ b/packages/ember-data/lib/system/store/container-instance-cache.js
@@ -46,9 +46,6 @@ Ember.merge(ContainerInstanceCache.prototype, {
       let instance = this.instanceFor(lookupKey);
 
       if (instance) {
-        if (fallback === '-default') {
-          instance.set('isNewSerializerAPI', true);
-        }
         return instance;
       }
     }