
878 A.2d 1189 (2005)
Anthony JEFFREY, Appellant,
v.
UNITED STATES, Appellee.
Nos. 01-CF-932, 04-CO-252.
District of Columbia Court of Appeals.
Argued May 3, 2005.
Decided June 30, 2005.
*1190 Thomas D. Engle, appointed by the court, for appellant.
Joycelyn S. Ballantine, Assistant United States Attorney, for appellee. Kenneth L. Wainstein, United States Attorney, John R. Fisher, Elizabeth Trosman, and Diane G. Lucas, Assistant United States Attorneys, were on the brief, for appellee.
Before TERRY, REID and WASHINGTON, Associate Judges.
WASHINGTON, Associate Judge.
After a jury trial, appellant Anthony Jeffrey ("Jeffrey") was convicted of carrying a pistol without a license ("CPWL") in a gun-free zone,[1] possession of an unregistered *1191 firearm,[2] and possession of ammunition.[3] On appeal, Jeffrey contends: (1) the trial court erred when it denied his D.C.Code § 23-110 motion alleging ineffective assistance of trial counsel; (2) the trial court erred when it refused to hold a hearing on his 23-110 motion or compel trial counsel to cooperate with his appellate counsel; and (3) the evidence was insufficient to support his enhanced conviction of carrying a pistol without a license in a gun-free zone. We affirm.

I.
As Jeffrey states in his brief on appeal, "[m]ost of the evidence at trial was not contested." The government's evidence showed that, at about 7:30 p.m. on August 14, 1999, Metropolitan Police Lieutenants Dianne Groomes and Edward Delgado were on patrol near the alley behind the 1200 block of Neal Street, Northeast. The officers had received complaints about the alley being used for drug deals and prostitution. According to the testimony, on the other side of the 1200 block of Neal Street, Northeast "is Wheatley Elementary School and the day care center and there is a playground area and the parking lot." As the officers approached the alley, they noticed a car blocking the alley. The officers noticed two people, one of whom was Jeffrey, in the car reclining back in their seats.
Lieutenant Delgado saw Jeffrey turn around to look at the officers from the front passenger's seat and then bend down toward the floorboard of the car. When the officers got out of their car to investigate, both officers also detected the smell of marijuana coming from the car. At this point, Jeffrey jumped out of the car and started walking to the front of the car. Lieutenant Groomes tried to block him and Jeffrey did "kind of like a little skirmish-type of a thing, kind of what we call on the street like a faking me out."
Lieutenant Delgado pulled Jeffrey onto the trunk of the car and put him in the frisk position. Because the car door was left ajar, Lieutenant Groomes noticed a barrel of a gun protruding from underneath the passenger's seat. The officers told the female passenger to stay seated in the car. According to Lieutenant Groomes, Jeffrey spontaneously told the officers that the female passenger had nothing to do with it, that it was his car and that he had just bought it. Lieutenant Delgado testified that Jeffrey also admitted that "[w]hatever is in the car is mine."
A crime scene search technician responded to the scene, saw the gun protruding from underneath the car seat, and took photographs. The technician also measured the distance from the location of the gun to the property line near the fence of Wheatley Elementary School, and testified at trial that the distance was 151 feet and 7 inches.
Jeffrey presented no evidence at trial. After deliberations, a jury found Jeffrey guilty of all counts. Jeffrey was sentenced on June 22, 2001, to multiple sentences of two years supervised probation, all to run concurrently. On May 17, 2002, Jeffrey's probation was revoked and he was sentenced to one to three months' incarceration.

II.

A. Jeffrey's Section 23-110 Motion
On October 16, 2002, Jeffrey filed an Ex Parte Motion to Compel Cooperation *1192 of Trial Counsel, which the trial court denied on November 4, 2002. The motion stated that cooperation of trial counsel was necessary to determine whether an ineffective assistance of counsel motion would be appropriate. On February 11, 2003, Jeffrey filed a Motion to Vacate Sentence pursuant to D.C.Code § 23-110 (2001) alleging ineffective assistance of trial counsel. Specifically, Jeffrey argued that trial counsel was ineffective because he should have put forth evidence showing that Jeffrey did not own the vehicle, and that, because of this, Jeffrey had no knowledge of the gun underneath the seat. Jeffrey contended that this evidence was crucial to his defense, and that, had his attorney established such facts, the outcome of his trial would have been different.
The trial court denied Jeffrey's motion on March 11, 2004. On appeal, Jeffrey challenges the trial court's denial of his § 23-110 motion on the merits, the trial court's denial of his motion without a hearing, and the trial court's denial of his motion to compel trial counsel to cooperate with appellate counsel for purposes of the § 23-110 motion.
The government opposed Jeffrey's § 23-110 motion arguing that Jeffrey had failed to show either deficient performance or prejudice from his trial counsel's alleged ineffectiveness. The government also argued, however, that because Jeffrey was no longer "in custody," the § 23-110 motion was not properly before the court.
On appeal, the government again argues that Jeffrey was not "in custody" at the time he filed his motion to vacate sentence under § 23-110, and thus, the motion was not properly before the trial court. The government points out that on May 17, 2002, Jeffrey was sentenced to one to three months incarceration and that, by February 11, 2003, when Jeffrey filed his motion, he had already served his sentence.
Upon a review of the record, we agree that the trial court lacked jurisdiction to hear Jeffrey's § 23-110 motion and, thus, his challenge to the trial court's ruling is not properly before this court. Although this precise argument was not made to the trial court, "jurisdictional challenges may be raised at any time." Friendship Hosp. for Animals, Inc. v. District of Columbia, 698 A.2d 1003, 1006 (D.C.1997). Motions made pursuant to § 23-110, under which Jeffrey sought relief, may only be made by a "prisoner in custody under sentence of the Superior Court." D.C.Code § 23-110(a) (2001) (emphasis added). Moreover, we have expressly held that "[t]o meet the in-custody requirement of § 23-110, a prisoner must currently be serving or detained upon a sentence imposed by the Superior Court." Thomas v. United States, 766 A.2d 50, 51 (D.C.2001). Because Jeffrey had already served his sentence, and therefore was not detained or in custody at the time he filed his § 23-110 motion, the motion was not properly before the trial court.
Because the trial court lacked jurisdiction to hear Jeffrey's ineffective assistance of counsel claim, we need not address whether the court erred substantively in denying the motion or whether it erred in refusing to hold a hearing on the matter. Furthermore, we need not address Jeffrey's claim that the court erred in denying his motion to compel, as this motion was directly related to his investigation on his § 23-110 motion.

B. Sufficiency of the Evidence
We now turn to Jeffrey's claims regarding his conviction for CPWL in a gun-free zone. Jeffrey argues that the trial court erred in allowing the jury to consider whether he carried a pistol without *1193 a license in a gun-free zone. The D.C.Code provides for an enhanced penalty to any person carrying a gun illegally within a gun-free zone, which includes: "[a]ll areas within 1000 feet of a public or private day care center, elementary school, vocational school, secondary school. . . ." § 22-3202.1 (1981). Jeffrey contends that, because the evidence at trial showed the distance of 151 feet 7 inches to be from the property line of the school, not the actual building itself, to the location of the gun in the car, the trial court erred in submitting that element to the jury. According to his interpretation of D.C.Code § 22-3202.1 (1981), a gun-free zone is that area within 1000 feet of an elementary school building itself, not within 1000 feet of the school grounds or the school's real property. Because "there was no testimony regarding the distance of Wheatley School from the property line or the distance between the gun and Wheatley School," Jeffrey contends, the elements of the statute were not met.
Because Jeffrey failed to raise this specific claim in the trial court, we would ordinarily review it for plain error. See Williams v. United States, 858 A.2d 984, 990 (D.C.2004). Because of the importance of the statutory interpretation issue, however, we have decided to review the case de novo. Our first step when interpreting a statute is to look at the language of the statute. See National Geographic Soc'y v. District of Columbia Dep't of Empl. Servs., 721 A.2d 618, 620 (D.C.1998). We are required to give effect to a statute's plain meaning if the words are clear and unambiguous. See Office of People's Counsel v. Public Serv. Comm'n, 477 A.2d 1079, 1083 (D.C.1984). "The primary and general rule of statutory construction is that the intent of the lawmaker is to be found in the language that he has used." Peoples Drug Stores, Inc. v. District of Columbia, 470 A.2d 751, 753 (D.C.1983). Furthermore, "in examining the statutory language, it is axiomatic that `the words of the statute should be construed according to their ordinary sense and with the meaning commonly attributed to them.'" Id. (quoting Davis v. United States, 397 A.2d 951, 956 (D.C.1979)).
"`The literal words of [a] statute, however, are not the sole index to legislative intent, but rather, are to be read in the light of the statute taken as a whole, and are to be given a sensible construction and one that would not work an obvious injustice.'" Columbia Plaza Tenants' Ass'n v. Columbia Plaza L.P., 869 A.2d 329, 332 (D.C.2005) (quoting Boyle v. Giral, 820 A.2d 561, 568 (D.C.2003)). We must also be mindful that our interpretation is not at variance with the policy of the legislation as a whole, "requiring that we remain more faithful to the purpose than the word." Id. (internal quotation marks omitted). Toward this end, in certain cases, we also consult the legislative history of a statute. See Abadie v. D.C. Contract Appeals Bd., 843 A.2d 738, 742 (D.C.2004).
Upon a review of the statute, its legislative history, and intended purpose, we hold that a gun-free zone as defined in D.C.Code § 22-3202.1 (1981), recodified at D.C.Code § 22-4502.01 (2001), is the zone within 1000 feet of the grounds and real property of a school, not just the building itself.
The text of the gun-free zone statute states:
(a) All areas within 1000 feet of a public or private day care center, elementary school, vocational school, secondary school, college, junior college, or university, or any public swimming pool, playground, video arcade, or youth center, or an event sponsored by any of the above *1194 entities shall be declared a gun free zone.
(b) Any person illegally carrying a gun within a gun free zone shall be punished by a fine up to twice that otherwise authorized to be imposed, by a term of imprisonment up to twice that otherwise authorized to be imposed, or both.
D.C.Code § 22-3202.1 (1981).
Here, although the statute does not explicitly state whether the grounds and real property of the buildings are included in the gun-free zone, it is evident that the statute is intended to protect children from being exposed to criminal activity. The legislative history of the statute makes this point clear. The Committee for the Judiciary of the Council of the District of Columbia stated that the legislation was prompted by gun violence continuing in places "where children abound." JAMES E. NATHANSON, BILL 10-265, THE "YOUTH FACILITIES FIREARM PROHIBITION AMENDMENT ACT OF 1994," COMM. ON THE JUDICIARY, at 2 (1994). "It is the intent of the bill to cover most places where children are intended to congregate." Id.
Jeffrey suggests that we read the statute to mean that a gun-free zone must be measured from the actual building itself to the locus of the gun. Were we to adopt Jeffrey's interpretation, however, we would lose sight of the legislative purpose and policy behind this provision. It is difficult to imagine why the legislature would consider only the area within 1000 feet of a school building to be a gun-free zone, but exclude the school grounds, upon which children are just as likely to linger and "abound."
Such an interpretation is also consistent with our cases interpreting the District drug-free zone statute, which is almost identical to the gun-free zone statute. See Boddie v. United States, 865 A.2d 544, 549 (D.C.2005); compare D.C.Code § 33-547.1 (1997 Supp.) with § 22-3202.1 (1981). Like the gun-free zone statute, the text of the drug-free zone statute does not expressly specify whether the zone includes the area within 1000 feet of the grounds of a school. In Boddie, we determined that because "the critical controlling language in the District's [drug-free zone] statute is virtually identical to that in the federal law," the statute should be interpreted in the same way the federal circuits had interpreted it. Boddie, 865 A.2d at 553. Similarly, it is appropriate for us to take guidance from the federal gun-free zone statute in interpreting our own version. Under the comparable federal statute, a "school zone" is defined as the area: (1) "in, or on the grounds of, a public, parochial or private school"; or (2) "within a distance of 1,000 feet from the grounds of a public, private or parochial school." 18 U.S.C. § 921(25) (emphasis added). We are satisfied that our interpretation of the D.C. gun-free zone statute is consistent with our federal counterpart.
Our interpretation is also consistent with our opinion in Goodson v. United States, 760 A.2d 551 (D.C.2000), in which we first addressed how distance is computed for the 1000-foot requirement in our drug-free zone statute.[4] We held that the evidence was insufficient to sustain appellant's conviction based on the fact that the end point (locus of the drug offense) of the measurement was incorrect. In so holding, however, we stated that: "we agree with the D.C. Circuit in interpreting the 1000-foot requirement `to mean the straight-line footage between the closest point within the real property of the school and the locus of the drug offense.'" Goodson, 760 A.2d at 554 (quoting United States v. Applewhite, *1195 315 U.S.App.D.C. 222, 226, 72 F.3d 140, 144 (1995)) (emphasis added).
Having found that a gun-free zone includes the area within 1000 feet of the grounds and real property of a school and not just the building itself, we now turn to whether the evidence at trial was sufficient to sustain Jeffrey's conviction. In this regard, we review a claim of insufficiency of evidence "in the light most favorable to the government, recognizing the province of the trier of fact to weigh the evidence, determine the credibility of the witnesses and to draw reasonable inferences from the testimony." Dickerson v. United States, 650 A.2d 680, 683 (D.C.1994). Because the undisputed evidence at trial showed that Jeffrey possessed the gun in this case 151 feet and 7 inches from the property line of Wheatley Elementary School, we find the evidence sufficient to sustain his conviction of CPWL in a gun-free zone.
Accordingly, we affirm the judgment of the trial court.[5]
So ordered.
NOTES
[1]  In violation of D.C.Code §§ 22-3202(a), -3202.1 (1981), recodified at D.C.Code §§ 22-4502(a), -4502.01 (2001).
[2]  In violation of D.C.Code § 6-2311(a) (1981), recodified at D.C.Code § 7-2502.01(a) (2001).
[3]  In violation of D.C.Code § 6-2361(3) (1981), recodified at D.C.Code § 7-2506.01(3) (2001).
[4]  See D.C.Code § 33-547.1 (1997 Supp.).
[5]  Jeffrey argues in the alternative that the trial court erred in instructing the jury that the government must prove that Jeffrey "carried the pistol on or about or within 1,000 feet of the real property of a public school." (Emphasis added). Given our decision in this case, we find that the trial court correctly instructed the jury.
