diff --git a/libguile/discouraged.h b/libguile/discouraged.h
index 1be05f0..0411069 100644
--- a/libguile/discouraged.h
+++ b/libguile/discouraged.h
@@ -54,6 +54,9 @@
 
 /* SCM_BOOL_NOT returns the other boolean.  
  * The order of ^s here is important for Borland C++ (!?!?!)
+ *
+ * XXX Should this handle %nil properly, and thus be
+ * defined as (scm_from_bool (scm_is_false_or_lisp_nil (x))) ?
  */
 #define SCM_BOOL_NOT(x)		(SCM_PACK (SCM_UNPACK (x) \
 					   ^ (SCM_UNPACK (SCM_BOOL_T) \
diff --git a/libguile/goops.c b/libguile/goops.c
index 1548472..b6234a6 100644
--- a/libguile/goops.c
+++ b/libguile/goops.c
@@ -190,11 +190,12 @@ SCM_DEFINE (scm_class_of, "class-of", 1, 0, 0,
       return scm_class_integer;
 
     case scm_tc3_imm24:
+      /* XXX What should be done with SCM_ELISP_NIL? */
       if (SCM_CHARP (x))
 	return scm_class_char;
-      else if (scm_is_bool (x))
+      else if (scm_is_bool_and_not_lisp_nil (x))
         return scm_class_boolean;
-      else if (scm_is_null (x))
+      else if (scm_is_null_and_not_lisp_nil (x))
         return scm_class_null;
       else
         return scm_class_unknown;