Following a jury trial, defendant was convicted of first-degree criminal sexual conduct. MCL 750.520b(l)(a); MSA 28.788(2)(l)(a). His sentence was sixty to ninety years in prison. On appeal, he argues that his conviction must be reversed, because the trial court failed to give the jury the insanity instruction before expert witnesses testified. He asserts, also, that he is entitled to resentencing, as his sentence is disproportionate and violates People v Moore, 432 Mich 311; 439 NW2d 684 (1989). We affirm defendant’s conviction, but remand for resentencing.
The underlying facts in this case are not in dispute. Defendant sexually assaulted a twelve-year-old boy in a public restroom of a department *592store. When apprehended outside the store, he said, "Thank God you’ve got me; it’s finally over.”
Defendant’s father testified that defendant had been adopted as an infant. Defendant’s biological family had a history of mental illness. Defendant was first treated for emotional problems while in kindergarten. During high school, he saw a psychologist and was prescribed the drug Stelazine to help control his mental problems. He stopped taking Stelazine in order to pass a military physical. After two years in the Navy, he was discharged for alcoholism. Defendant did not take Stelazine while in the Navy or after he was discharged. The instant assault occurred less than a year after his discharge from the Navy.
Dr. Ryan, a clinical psychologist, treated defendant while he was in high school. He diagnosed defendant as a schizophrenic. Dr. Tanay, a psychiatrist, evaluated defendant pursuant to court order. Dr. Tanay was not certain whether defendant had schizophrenia, but he had no doubt that defendant was mentally ill. He believed defendant was legally insane at the time of the assault; as a result of his mental illness, defendant could not conform his conduct to the law.
The prosecution called psychologist Dr. Carole Holden as a rebuttal witness. In her opinion, defendant was not mentally ill when the assault occurred; he knew it was wrong to act on his sexual impulses, but did so heedless of the consequences. She agreed that defendant had a psychological disorder, but she saw no evidence of schizophrenia.
i
On appeal, defendant argues that the trial court erred in failing to give the legal insanity jury *593instruction before the experts took the stand. CJI2d 7.9. Defendant did not request the instruction prior to the testimony. Section 29a(l) of the Code of Criminal Procedure provides in part:
If the defendant asserts a defense of insanity in a criminal action which is tried before a jury, the judge shall, before testimony is presented on that issue, instruct the jury on the law as contained in sections 400a and 500(g) of Act No. 258 of the Public Acts of 1974 and in section 21a of chapter 8 of this act. [MCL 768.29a(l); MSA 28.1052(1X1).]
In this case, the trial court was required by statute to define mental illness and legal insanity before taking expert testimony on the insanity defense. MCL 330.1400a; MSA 14.800(400a); MCL 768.21a; MSA 28.1044(1). It neglected to do so.
Another panel of this Court has concluded that the failure of the trial court to instruct on legal insanity before taking expert testimony on the subject is always reversible error. People v Mikulin, 84 Mich App 705, 707-708; 270 NW2d 500 (1978). This is true even if the instruction is not requested. Id. In Mikulin, the Court indicated that the purpose of § 29a(l) is to prepare the jury for the proposed expert testimony. Id., 708. Due to the mandatory language in the statute, it reasoned, the Legislature must have concluded that the instruction is essential for a fair disposition of an insanity claim. Id.
Subsequent panels of this Court have held that the failure to properly instruct on legal insanity may be harmless error. See People v Mazzie, 137 Mich App 60, 66; 357 NW2d 805 (1984), aff'd 429 Mich 29; 413 NW2d 1 (1987), citing People v Crawford, 89 Mich App 30; 279 NW2d 560 (1979). In Crawford, the defendant presented an insanity defense, but was convicted of second-degree mur*594der. Although some of the jury instructions pertaining to the insanity defense were erroneous, any error was harmless, because the jury found the defendant guilty, as opposed to guilty but mentally ill. Therefore, it could not have rendered a verdict of not guilty by reason of insanity; by definition, a person must be mentally ill in order to be found legally insane. Id., 36; MCL 768.21a(l); MSA 28.1052(1)(1).
Neither Crawford nor Mazzie addressed that part of § 29a(l) which mandates that trial courts instruct on legal insanity before the experts testify. See Mikulin, supra. Moreover, it is unclear from the opinions in those two cases whether the juries were instructed before the experts’ testimony or later. Therefore, we must determine if the Crawford harmless error analysis should be applied where, as here, clearly no preliminary insanity instruction was given. See People v Girard, 96 Mich App 594, 603; 293 NW2d 639 (1980).
Prior to the expert’s testimony in Girard, the trial court erroneously defined insanity and failed to define mental illness. Id., 602. This Court indicated that it is critical to the Crawford harmless error analysis that the jury be properly instructed on the distinctions between mental illness and legal insanity. Id., 603. The trial court also confused the concepts of mental illness and insanity in the final instructions. Due to this confusion, the Court refused to apply the harmless error analysis and reversed defendant’s second-degree murder conviction. See also People v Giuchici, 118 Mich App 252; 324 NW2d 593 (1982).
In Giuchici, the trial court’s preliminary insanity jury instruction was ambiguous and confusing. Id., 264. However, the defendant’s guilty but mentally ill, first-degree murder conviction was af*595firmed on appeal. No manifest injustice resulted by the erroneous preliminary instruction, because the insanity instructions given at the end of trial were correct and clarified any ambiguity. Id., 265.
Both Giuchici and Girard recognize that "erroneous” preliminary insanity jury instructions may be harmless error. By analogy, we conclude that the failure to give any preliminary insanity jury instruction may also be harmless error. Section 29a(l) of the Code of Criminal Procedure does not prevent us from applying a harmless error analysis to the facts of this case. Normally, we reverse a conviction only if the error complained of has resulted in a miscarriage of justice. MCL 769.26; MSA 28.1096.
The trial court in this case failed to define mental illness and legal insanity prior to the experts’ testimony; it properly instructed the jury on both concepts at the end of the trial. The fact that correct instructions were given coupled with defendant’s failure to object may be sufficient to find the error harmless. See Giuchici, 265. Moreover, unlike Girard, the judge here properly instructed the jury at the end of the trial on the distinctions between mental illness and insanity. Girard, 602-603. Therefore, the Crawford harmless error analysis applies to this case. Our decision is influenced by the fact that the jury found defendant guilty as opposed to guilty, but mentally ill. Given that finding, it is illogical to expect that the jury could have rendered a verdict of not guilty by reason of insanity. Therefore, it was irrelevant that the distinction between mental illness and legal insanity was not explained to the jury before the experts testified. We conclude that manifest injustice did not result from the trial court’s failure preliminarily to give the insanity and the mental illness jury instructions. See Crawford, 36; *596People v Van Dorsten, 441 Mich 540; 494 NW2d 737 (1993).
ii
Defendant was twenty-two years old when sentenced to a minimum prison term of sixty years. He argues that the sentence violates Moore. We disagree.
In determining whether a defendant has a reasonable prospect of actually serving a sentence, the appellate court properly takes into account possible disciplinary credits. People v Rushlow, 437 Mich 149, 155; 468 NW2d 487 (1991). Even without disciplinary credits, defendant will be in his early eighties when his minimum term ends. We are bound by this Court’s precedent which requires us reasonably to expect that a defendant may live into his eighties in prison. People v Schollaert, 194 Mich App 158, 171; 486 NW2d 312 (1991), citing People v Redman, 188 Mich App 516, 518; 470 NW2d 676 (1991). Administrative Order No 1990-6, 436 Mich lxxxiv, as extended by Administrative Order No 1991-11, 439 Mich cxliv, as extended by Administrative Order No 1992-8, 441 Mich cxi. Therefore, we find no violation of Moore.
However, defendant’s sentence does violate People v Milbourn, 435 Mich 630; 461 NW2d 1 (1990). The sentencing guidelines’ recommended minimum sentence range is ten to twenty-five years in prison. The trial court exceeded the guidelines, saying they failed to account for defendant’s prior juvenile record or two prior similar offenses. The trial court did not have the benefit of Milbourn at the time of sentencing. Milbourn, supra.
Sentences within the guidelines are presumptively not excessively severe or unfairly disparate. People v Broden, 428 Mich 343, 354; 408 NW2d *597789 (1987). Trial courts should not depart from the guidelines, unless there are circumstances about the offense or offender not reflected there. Milbourn, 659-660. Even where some departure appears to be appropriate, the extent of it may constitute a violation of the principle of proportionality. Id., 660.
Here, the trial court sentenced defendant to a term more than double the maximum minimum term recommended by the sentencing guidelines. As a juvenile, defendant had been placed on one-year probation for a similar offense. Defendant also admitted to Dr. Tanay that, while he was in the Navy, he had sexual activities with his girlfriend’s children. These circumstances concerning the offender were not reflected in the guidelines’ recommendation. Id., 659-660.
Although we believe a departure from the guidelines is appropriate, we believe that such a severe departure as occurred here is unwarranted and violates the principle of proportionality. Therefore, we vacate defendant’s sentence.
The conviction is affirmed. The sentence is vacated and the case remanded for resentencing.
Connor, J., concurred.