[¶ 1] This is an appeal from the circuit court’s denial of writ of habeas corpus. Alvia O. Lewis (Lewis) contends that the South Dakota Board of Pardons and Paroles refusal to give him credit for the sixteen months that he was serving in the Colorado State Penitentiary was a violation of the constitutional prohibition against ex post facto laws. We affirm.
FACTS
[¶2] On September 27, 1985, Lewis was sentenced on charges of aggravated assault and third degree burglary in Pennington County.
[¶3] On the aggravated assault charge, Lewis received a suspended imposition of sentence, was placed on probation for four years and ordered to serve six months in the Pennington County Jail. On the third degree burglary charge, Lewis received a suspended imposition of sentence, was placed on probation for four years, and ordered to serve sixty days in the Pennington County Jail. The county jail sentences on both charges were to run consecutively, however, the terms of probation were to run concurrently.
[¶ 4] Lewis admitted a probation violation on both charges on February 27, 1987. The circuit judge revoked his suspended imposition of sentence on March 9, 1987. The judge ordered Lewis to be committed to the South Dakota State Penitentiary for ten years, with five years suspended on each count.
[¶ 5] Lewis was released on parole on June 12, 1990, with supervision in the state of Colorado through the Interstate Compact Agreement. SDCL 24-16-1 to SDCL 24-16-5. On May 20,1993, Lewis was sentenced in Colorado to four years plus parole on a vehicular assault charge. While Lewis was imprisoned in the Colorado Penitentiary, the South Dakota Board of Pardons and Paroles issued a warrant of arrest for an alleged parole violation.
[¶ 6] Pursuant to SDCL 24-15-21 the South Dakota Board of Pardons and Paroles alleged that it was authorized to suspended *63the running of the parole time from when the warrant was issued on June 15, 1993, to the final parole revocation on October 16, 1994. After issuance of a detainer Lewis was returned to South Dakota for a parole revocation hearing on October 26,1994.
[¶ 7] Lewis asked the Colorado court to allow him to serve his Colorado and South Dakota sentences concurrently. The Colorado court denied his request. He also asked South Dakota Board of Pardons and Paroles for credit for the time that he had spent in the Colorado Penitentiary from the time the warrant of arrest was issued on June 15, 1993, to the final revocation order on October 16, 1994. This request was also denied. Lewis’ parole was revoked and he was sentenced to the five years remaining on his suspended sentences.
STANDARD OF REVIEW
[¶8] Since habeas corpus is in the nature of a collateral attack on a final judgment, the scope of review is limited to:
(1) whether the court had jurisdiction of the crime and the person of the defendant; (2) whether the sentence was authorized by law; and (3) in certain cases, whether an incarcerated defendant has been deprived of basic constitutional rights.
Petrilli v. Lewpley, 491 N.W.2d 79, 81 (S.D.1992).
[¶ 9] In context of post conviction attacks on the conviction itself, habeas corpus reaches only jurisdictional error. Goodroad v. Solem, 406 N.W.2d 141 (S.D.1987). Ex post facto claims are an issue of law, and are reviewed de novo with facts being set aside only if clearly erroneous. State v. Karp, 527 N.W.2d 912 (S.D.1995).
ANALYSIS
[¶ 10] SDCL 24-15-21 was amended in 1986 and provides:
If the executive director of the board is satisfied that any provisions of § 2⅛-15-20 has been violated the executive director may issue a warrant to the Department of Corrections, any law enforcement officer, or any parole agent, directing that the parolee named be arrested. Pursuant to the provision of § 24^15-23, the parolee may be returned to the state penitentiary. Upon the issuance of the warrant, the running of the parole supervision time shall- be suspended until the board has entered its final order on the revocation. The board shall credit the inmate with time spent in custody as a direct result of the parole violation, (emphasis added).
[¶ 11] Lewis is seeking credit for the sixteen months he served from the issuance of the South Dakota Board of Pardons and Paroles arrest warrant on June 15, 1993 to the final parole revocation hearing on October 16,1994.
[¶ 12] Lewis points out that his original offenses of aggravated assault and third degree burglary were committed in 1985 prior to the 1986 amendment to SDCL 24-15-21 allowing the suspension of the parole violation. He argues that since the parole violation was related to these original offenses, the denial of credit to him for the sixteen months served in Colorado after the issuance of the arrest warrant is a violation of the ex post facto clause.
[¶ 13] The state argues that SDCL 24^15-21 only applies to parolees at large and it did not apply in Lewis’ case since he was not at large. It argues that SDCL 24-15-21 amended in 1986 was in effect when his probation was revoked, when he was sentenced to the South Dakota State Penitentiary, and when his parole was revoked in October 1994. It is therefore the state’s position that it is not an ex post facto law.
[¶ 14] The trial court held that Lewis was not entitled to sixteen months credit for time served in Colorado. SDCL 24-15-21 was applicable to Lewis because the statute was in effect when he was under the control of the executive branch and subject to the South Dakota Board of Pardon and Paroles. Relying on State v. Karp, 527 N.W.2d at 913, the trial court stated that sentences must be served consecutively because the defendant is “under process of law” and not entitled to credit for time served.
[¶ 15] The United States Supreme Court has held that ex post facto clause is aimed at laws that “retroactively alter the definition of *64crimes or increase the punishment for criminal acts.” Cal. Dept. of Corrections v. Morales, 514 U.S. 499, 504, 115 S.Ct. 1597, 1601, 131 L.Ed.2d 588, 594 (1995). The South Dakota Supreme Court has explained the ex post facto prohibition.
In Delano v. Petteys, 520 N.W.2d 606, 608 (S.D.1994), this Court stated:
The ex post facto prohibition forbids the Congress and the States to enact any law “which imposes a punishment for an act which was not punishable at the time it was committed, or imposes additional punishment'to that then prescribed....’
State v. McGill, 536 N.W.2d 89, 93 (S.D.1995).
[¶ 16] The constitutional prohibition on ex post facto laws applies only to statutes that impose penalties, are retrospective, and in general, are not procedural nor change the ingredients of the offense or the ultimate facts necessary to establish guilt. Collins v. Youngblood, 497 U.S. 37, 41, 110 S.Ct. 2715, 2718-19, 111 L.Ed.2d 30 (1990) on remand Youngblood v. Collins, 909 F.2d 803 (5th Cir.1990); Weaver v. Graham, 450 U.S. 24, 101 S.Ct. 960, 67 L.Ed.2d 17 (1981); Snyder v. State, 912 P.2d 1127 (Wyo.1996); Stumes v. Delano, 508 N.W.2d 366 (S.D.1993).
[¶ 17] The purpose underlying the proscription against ex post facto legislation is to ensure that legislative enactments provide “fair warning of their effect,” in order that individuals may rely on the meaning and extent of the statutes until they have been formally and explicitly revised. Weaver v. Graham, supra; See People v. Bowring, 902 P.2d 911 (Colo.App.1995).
[¶ 18] Lewis argues that the reasoning of Williams v. Lee, 33 F.3d 1010 (8th Cir.1994) supports his position that the suspension of parole supervision time is violative of the prohibition against ex post facto laws. See Beebe v. Phelps, 650 F.2d 774 (5th Cir.1981) (which held that the forfeiting or revocation of good time credits as being an ex post facto law).
[¶ 19] The Eighth Circuit Court of Appeals found Williams’ good time credits had been forfeited by subsequent legislation (SDCL 24A15-24) and such forfeiture was constitutionally in violation of ex post facto clause. However, Lewis’ reliance under these circumstances is misplaced. The Circuit Court of Appeals in Williams stated that, “[h]aving determined that the state could not constitutionally revoke Williams’ good time credits, we conclude that, regardless of whether the tolling provision was ex post facto as applied to Williams (an issue we need not and do not reach).” Williams, 33 F.3d at 1014 (8th Cir.1994).
[IF 20] The statutes that create good time enumerate certain criteria which must be met in order for inmates to be entitled to good time. SDCL 24-5-1. The right to a reduction for good conduct is absolute and cannot be granted or taken away arbitrarily. See South Dakota v. Weekley, 90 S.D. 192, 240 N.W.2d 80 (1976).
[¶ 21] The United States Supreme Court has ruled that due process of law attaches to good time credit that an inmate earns pursuant to state law, and that certain minimal due process procedures must be followed before good time may be revoked. Wolff v. McDonnell, 418 U.S. 539, 94 S.Ct. 2963, 41 L.Ed.2d 935 (1974); Preiser v. Rodriguez, 411 U.S. 475, 93 S.Ct. 1827, 36 L.Ed.2d 439 (1973). Legislation affecting the revocation or forfeiture of good time credits can be void due to violations of ex post facto law and the right to minimal due process procedures. See Weekley, 90 S.D. 192, 240 N.W.2d 80.
[¶ 22] In addressing the first element of the ex post facto clauses of the state and federal constitutions, the “critical question is whether the law changes the legal consequences of acts completed before its effective date.” Weaver, 450 U.S. at 31, 101 S.Ct. at 966, 67 L.Ed.2d at 24. For example in Weaver, the Supreme Court held unconstitutional a Florida statute that automatically reduced the amount of “gain time”1 for good *65conduct and obedience to prison rules that could be deducted in the calculation of an inmate’s sentence, because the self operative statute was applied to prisoners who had been convicted for acts committed before the statute’s effective date, i.e., the original felony convictions. The Supreme Court held that the application of the Florida statute was retrospective in the ex post facto sense because it substantially altered the consequences attached, not to conduct occurring after the law’s effective date, but rather to criminal activities completed. 450 U.S. at 31, 101 S.Ct. at 965-66, 67 L.Ed.2d at 24.
[¶ 23] While it is settled that criminal or penal legislation amending existing law may not change the legal consequences of acts completed before its effective date, a statute, however, is not rendered unconstitutional as an ex post facto law merely because it might operate on a fact or status preexisting the effective date of the legislation, as long as its punitive features apply only to acts committed after the statutory proscription becomes effective. In re Ramirez, 39 Cal.3d 931, 218 Cal.Rptr. 324, 705 P.2d 897 (1985); People v. Billips, 652 P.2d 1060 (Colo.1982); Gasper v. Gunter, 851 P.2d 912 (Colo.1993). In Billips, the defendant challenged a statute which provided that, for purposes of classifying the crime of escape from incarceration, persons in confinement for previously nonelassified felonies were deemed to have been convicted of a Class 5 felony. The statute was held to be retrospective and thus violated the federal and state prohibitions against ex post facto legislation. The Supreme Court of Colorado held that because the contested statutory provision gave notice to the defendant and others who commenced service of a sentence for a felony conviction prior to the statute’s effective date and further because the defendant’s escape took place ... well after the effective date of the challenged statute, no retrospective application is involved. Billips, 652 P.2d at 1065.
[¶ 24] Sentence enhancement statutes have long withstood ex post facto clause challenges. See Gryger v. Burke, 334 U.S. 728, 68 S.Ct. 1256, 92 L.Ed. 1683 (1948) (use of prior felony conviction as basis for habitual criminal adjudication does not violate ex post facto clause, even though the conviction occurred prior to passage of habitual criminal act); McDonald v. Massachusetts, 180 U.S. 311, 21 S.Ct. 389, 45 L.Ed. 542 (1901) (habitual criminal statute imposes a punishment on none but future crimes and therefore is not ex post facto;) United States v. Leonard, 868 F.2d 1393 (5th Cir.1989) (statute which based enhancement of defendant’s sentence upon convictions proceeding its enactment held not retrospective).
[¶ 25] In the context of ex post facto challenges to criminal or penal statutes, we have followed Weaver (holding that two critical elements must be present for a criminal or penal law to be ex post facto: it must be retrospective, that is, it must apply to events occurring before its enactment, and it must disadvantage the offender affected by it); In re Williams, 488 N.W.2d 667 (S.D.1992); Stumes, 508 N.W.2d 366.
[¶26] Relying on Williams, supra, petitioner contends that the 1986 amendments relate to the original offense and not to the new crime committed in Colorado. While it is true that the 1986 amendment to SDCL 24-15-21 applies to petitioner only because he is a parolee and that he is a parolee because of an act committed before the 1986 amendment to SDCL 24-15-21, the suspension of parole supervision time is imposed solely because of the new crimes which the petitioner was sentenced to in the State of Colorado occurring after the 1986 amendment to SDCL 24-15-21. In other words the 1986 amendment to SDCL 24-15-21 applies only to events occurring after their enactment. If any aspect of petitioner’s life is unconnected to petitioner’s original crime, it would seem that crimes he committed in the State of Colorado after he was paroled would be unconnected. Accordingly, the 1986 amendment to SDCL 24-15-21 which suspended the parole supervision time after a warrant of arrest is issued does not relate to petitioner’s original crime and is not retrospective under Weaver or Stumes, supra.
[¶ 27] The amendment to the SDCL 24-15-24 addressing the tolling of parole supervision time was in effect on July 1, 1986. Lewis violated his probation on February 27, *661987, and his parole on May 20, 1993, (Colorado conviction) for which a warrant of arrest was issued on June 15, 1993. Thus Lewis had “fair warning” of the consequences of violating the conditions of his probation which were triggered by Lewis’ acts which were committed after the statute became effective.
[¶28] We conclude that.the 1986 amendment SDCL 24-15-21 is not retrospective and therefore does not violate the ex post facto clauses.2
[¶ 29] We have already ruled that granting credit to a parolee for time served in another jurisdiction is within the Board of Pardons and Paroles’ discretion. Bush v. Canary, 286 N.W.2d 536 (S.D.1979). Parolees have no constitutional right to receive concurrent sentences. See Moody v. Daggett, 429 U.S. 78, 97 S.Ct. 274, 50 L.Ed.2d 236 (1976).
[¶ 30] Neither has South Dakota, by statute or otherwise, conferred such a right upon parolees.
[¶31] In State v. Moliga, 113 Idaho 672, 747 P.2d 81 (1987) the court held that the defendant had no constitutional right to serve his sentences for Washington crimes and Idaho crimes concurrently. See State v. Teal, 105 Idaho 501, 670 P.2d 908 (1983); In re Rojas, 23 Cal.3d 152, 151 Cal.Rptr. 649, 588 P.2d 789 (1979); Woodson v. State, 178 Ind.App. 692, 383 N.E.2d 1096 (1978) all reaching a similar result.
[¶ 32] The Board of Pardons and Paroles has the authority to grant the petitioner a retroactive credit for the time served in Colorado and may even decide not to revoke petitioner’s.parole notwithstanding the Colorado conviction, and the Board’s decision is purely discretionary. Bush at 539.
[¶ 33] The judgment of the circuit court denying the writ of habeas corpus is hereby affirmed.3 Accordingly, Lewis is not entitled to a writ of habeas corpus.
[¶ 34] AMUNDSON and GILBERTSON, JJ., concur. [¶ 35] MILLER, C.J., concurs specially. [¶ 36] SABERS, J., dissents. [¶ 37] MOSES, Circuit Judge, for KONENKAMP, J., disqualified.. "Gain time" refers to time credited to decrease an inmate's prison term "for meritorious conduct or exceptional industry.” Weaver, 450 U.S. at 25 n. 1, 101 S.Ct. at 962 n. 1, 67 L.Ed.2d at 21 n. 1.
. This is the same holding as in Williams, 488 N.W.2d 667. In that case SDCL 24-15-21 was enacted before the time that Williams was convicted of passing fraudulent checks in South Carolina. Thus the 1986 statute was not being applied to conduct which occurred before its enactment, and we held that was no retrospective application and accordingly no valid ex post fac-to objection.
. Although the trial court may have denied the writ for wrong reason, we will not overturn a right result even though it is based on wrong reason. See Seymour v. Western Dakota Voc. Tech. Institute, 419 N.W.2d 206 (S.D.1988), Estate of Quinn, 450 N.W.2d 432 (S.D.1990).