(eval-when (#-sb-xc :compile-toplevel :load-toplevel :execute)
-(define-condition duplicate-case-key-warning (style-warning)
+;;; Make this a full warning during SBCL build.
+(define-condition duplicate-case-key-warning (#-sb-xc-host style-warning #+sb-xc-host warning)
((key :initarg :key
:reader case-warning-key)
(case-kind :initarg :case-kind