thodg/cl-positional-numbers

diff --git a/positional.lisp b/positional.lisp
index caea7ac..444800b 100644
--- a/positional.lisp
+++ b/positional.lisp
@@ -16,6 +16,8 @@
 (defgeneric base-parse (base input))
 (defgeneric base-positional (base number))
 
+(declaim (type simple-string *integer-base*))
+
 (defvar *integer-base*
   "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz")