Index: /trunk/ccl/level-1/l1-typesys.lisp
===================================================================
--- /trunk/ccl/level-1/l1-typesys.lisp	(revision 354)
+++ /trunk/ccl/level-1/l1-typesys.lisp	(revision 355)
@@ -3623,5 +3623,5 @@
 (deftype signed-byte (&optional s)
   (cond ((eq s '*) 'integer)
-	  ((and (integerp s) (> s 1))
+	  ((and (integerp s) (> s 0))
 	   (let ((bound (ash 1 (1- s))))
 	     `(integer ,(- bound) ,(1- bound))))