diff --git a/src/decoder.lisp b/src/decoder.lisp
index 7686d96..f0ad423 100644
--- a/src/decoder.lisp
+++ b/src/decoder.lisp
@@ -103,7 +103,7 @@ as a string."
         (read-part Int nil #\-)
         (read-part Frac #\.)
         (read-part Exp #\e #\- #\+)
-        (if c (unread-char c stream))
+	(when c (unread-char c stream))
         (values category (coerce (cdr chars) 'string))))))
 
 (defun read-json-name-token (stream)
diff --git a/src/objects.lisp b/src/objects.lisp
index 08cade0..4d56a1f 100644
--- a/src/objects.lisp
+++ b/src/objects.lisp
@@ -63,7 +63,8 @@ registered in the superclass."
 (eval-when (:compile-toplevel :load-toplevel :execute)
  (defclass fluid-object (standard-object) ()
    (:documentation "Any instance of a fluid class.")
-   (:metaclass fluid-class)))
+   (:metaclass fluid-class))
+ (finalize-inheritance (find-class 'fluid-object)))
 
 (defmethod compute-class-precedence-list ((class fluid-class))
   "Objects of fluid classes are fluid objects."