Fix FORMAT specifier X.

diff --git a/src/boot.lisp b/src/boot.lisp
index d233b93..5f6bbca 100644 (file)
--- a/src/boot.lisp
+++ b/src/boot.lisp
@@ -520,7 +520,7 @@
     `(let ((,g!x ,x))
        (typecase ,g!x
          ,@clausules
-         (t (error "~X fell through etypecase expression." ,g!x))))))
+         (t (error "~S fell through etypecase expression." ,g!x))))))
 
 (defun notany (fn seq)
   (not (some fn seq)))