diff --git a/level2/package.lisp b/level2/package.lisp
index 66078a8..b464c3b 100644
--- a/level2/package.lisp
+++ b/level2/package.lisp
@@ -40,6 +40,7 @@
            :alist
            :plist
            :property
+           :property!
            :access
            :$guard1
            :$or1