Every conveyance or charge of or upon any estate or interest in lands containing any provision for the revocation, determination or alteration of such estate or interest or any part thereof, at the will of the grantor, shall be void as against subsequent purchasers from such grantor for a valuable consideration of any estate or interest so liable to be revoked or determined, although the same be not expressly revoked, determined or altered by such grantor by virtue of the power reserved or expressed in such prior conveyance or charge.
Wis. Stat. § 240.03