--- src/utils/hashfn.lisp.orig	2011-04-15 11:45:05.000000000 -0600
+++ src/utils/hashfn.lisp	2012-01-20 12:07:51.141297752 -0700
@@ -76,8 +76,7 @@
     #+(and allegro (not 64bit)) 24
     #+(and allegro 64bit) 32
     #+cmu 29
-    #+(and sbcl (not x86-64)) 29
-    #+(and sbcl x86-64) 60))
+    #+sbcl sb-vm:n-positive-fixnum-bits))
 
 (defconstant-if-unbound pvs-sxhash-byte
   (byte pvs-sxhash-bits 0))