Appellant seeks review of the trial court's order denying his motion for post-conviction relief, filed pursuant to Florida Rule of Criminal Procedure 3.850. As grounds for relief, the motion alleged sentencing error in the trial court’s retention of jurisdiction over twenty years of the first one-third of a life sentence. It is improper to retain jurisdiction over a portion of a life sentence. State v. Mobley, 481 So.2d 481 (Fla. 1986); Clark v. State, 489 So.2d 1166 (Fla. 1st DCA 1986); Frazier v. State, 488 So.2d 166 (Fla. 1st DCA 1986), review denied, 494 So.2d 1150 (Fla. 1986); Stettler v. State, 475 So.2d 1009 (Fla. 1st DCA 1985). Accordingly, we treat appellant’s motion as a rule 3.800(a) motion to correct illegal sentence, and remand with *1015directions to strike the retention of jurisdiction over a portion of the life sentence.