We reverse the trial court’s refusal to allow defendant to withdraw his plea. His motion was timely, and therefore the issue is preserved. See Haag v. State, 591 So.2d 614 (Fla. 1992) (mail box rule applied to prisoner filings; papers deemed filed when placed in hands of prison authorities for mailing). The record discloses beyond any doubt that the trial court failed to advise defendant of the mandatory minimum penalties that would have to be assessed. On remand the court shall allow defendant to withdraw his plea and begin anew.