```common lisp
(in-package #:asdf-user)

(defsystem #:sicl-additional-types
  :components
  ((:file "packages")
   (:file "types" :depends-on ("packages"))))
```

Use explicit package prefix for IN-PACKAGE.
user
```common lisp
(cl:in-package #:asdf-user)

(defsystem #:sicl-additional-types
  :components
  ((:file "packages")
   (:file "types" :depends-on ("packages"))))
```
assistant