diff --git a/app/serializers/rest/account_serializer.rb b/app/serializers/rest/account_serializer.rb
index 219f8075ae53925073873f8ef51b2c04bff6e5c5..a78ec45073ada27e8d3e062cc6dc396ac23bcb2f 100644
--- a/app/serializers/rest/account_serializer.rb
+++ b/app/serializers/rest/account_serializer.rb
@@ -56,7 +56,7 @@ class REST::AccountSerializer < ActiveModel::Serializer
   end
 
   def created_at
-    object.created_at.midnight.iso8601
+    object.created_at.midnight.as_json
   end
 
   def last_status_at