((sb!xc:subtypep data-type 'vector)
(let ((ctype (sb!kernel:specifier-type data-type)))
(when (sb!kernel:array-type-p ctype)
- (let ((etype (sb!kernel:array-type-element-type ctype)))
+ (let ((etype (sb!kernel:type-*-to-t
+ (sb!kernel:array-type-specialized-element-type ctype))))
(make-array 0 :element-type (sb!kernel:type-specifier etype))))))
(t
nil)))