P ER C URIAM .

Michael Dunbar appeals an order summarily denying his motion for postconviction relief filed under Florida Rule of Criminal Procedure 3.800(a). Dunbar asserted that his life sentence for attempted first-degree murder was illegal. The trial court determined that Dunbar’s sentence not illegal because his life sentence was authorized under section 775.087(2)(a)(3), Florida Statutes. (2007). Finding no error by the trial court, we affirm.

We also conclude that this appeal is frivolous. This appeal marks Dunbar’s fourth collateral attack on his 2008 judgment and sentence in Duval County Circuit Court Case Number 07-13715 CFA. He appealed from orders denying postconviction relief in *2 these cases: 1D10-6449, 1D14-3481, and 1D15-2577. Dunbar received no relief in any of these cases. The court warns Dunbar that any future filings that this court determines to be frivolous may result in the imposition of sanctions, including a prohibition against any further pro se filings in this court and a referral to the appropriate institution or facility of Florida Department of Corrections for disciplinary procedures. See § 944.279, Fla. Stat. (2020) (providing that “[a] prisoner who is found by a court to have brought a frivolous or malicious suit, action, claim, proceeding, or appeal . . . or to have brought a frivolous or malicious collateral criminal proceeding . . . is subject to disciplinary procedures pursuant to the rules of the Department of Corrections”).

A FFIRMED .

R OWE , C.J., and L EWIS and W INOKUR , JJ., concur.

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Not final until disposition of any timely and authorized motion under Fla. R. App. P. 9.330 or 9.331 .

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Michael Dunbar, pro se, Appellant.

Ashley Moody, Attorney General, Tallahassee, for Appellee.

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