FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                 No. 06-50487
                Plaintiff-Appellee,
                                             D.C. No.
               v.
                                          CR-05-00285-
JOSEPH MANUEL ZALAPA, aka                     DDP-1
Joseph Manual Zalapa,
                                            OPINION
             Defendant-Appellant.
                                      
       Appeal from the United States District Court
          for the Central District of California
       Dean D. Pregerson, District Judge, Presiding

                 Argued and Submitted
        September 28, 2007—Pasadena, California

                  Filed December 5, 2007

      Before: Thomas G. Nelson, Sandra S. Ikuta, and
              N. Randy Smith, Circuit Judges.

             Opinion by Judge N. Randy Smith




                           15963
                   UNITED STATES v. ZALAPA              15965


                         COUNSEL

James H. Locklin, Deputy Federal Public Defender, Los
Angeles, California for the defendant-appellant.

Bayron T. Gilchrist, Assistant United States Attorney, Los
Angeles California, for the plaintiff-appellee.


                         OPINION

N.R. SMITH, Circuit Judge:

  We hold that a defendant who fails to object in the district
court to multiplicitous convictions and sentences does not
15966              UNITED STATES v. ZALAPA
waive his or her right to raise a double jeopardy challenge on
appeal. Because we conclude that the district court plainly
erred by sentencing the appellant Joseph Manuel Zalapa on
multiplicitous firearm counts and entering judgment, we
reverse.

         I.   Factual and Procedural Background

   On October 20, 2005, officers in the Santa Ana, California
Police Department (“SAPD”) were in a parking lot investigat-
ing the presence of a stolen vehicle. While in the parking lot,
the officers observed Zalapa and another man “acting suspi-
ciously.” At that time, Zalapa was carrying a backpack. The
officers attempted to approach Zalapa and his companion.
When approached by the SAPD officers, Zalapa fled in one
direction and his companion fled in another. In the course of
attempting to elude the officers, Zalapa dumped the backpack
over a fence in the yard of a home that he passed along his
intended escape route. The officers apprehended Zalapa
shortly thereafter. They recovered Zalapa’s backpack after a
resident of the home discovered it and turned it in to the
police. Zalapa’s backpack contained 64 rounds of 9mm
ammunition, a magazine loaded with 29 rounds of 9mm
ammunition, and a Sten M-5 rifle.

   At the time Zalapa was arrested, he was on probation for
a prior felony drug offense involving a firearm. As a term and
condition of his probation, he was prohibited from possessing
a firearm or ammunition.

   A federal grand jury indicted Zalapa on three felony
counts: possession of ammunition by a convicted felon (Count
One); possession of an unregistered machine gun (Count
Two); and possession of an unregistered firearm with a barrel
less than 16 inches long (Count Three). Counts Two and
Three charged Zalapa with violating 26 U.S.C. § 5861(d),
which provides that “[i]t shall be unlawful for any person . . .
to receive or possess a firearm which is not registered to him
                    UNITED STATES v. ZALAPA                15967
in the National Firearms Registration and Transfer Record.”
There is no dispute that both firearm counts arose out of pos-
session of a single unregistered firearm — a Sten, model M-
5, 9mm machine gun, serial number 237508.

   Zalapa pleaded guilty, without a plea agreement. Zalapa did
not object to Counts Two and Three before he entered a guilty
plea. The district court sentenced Zalapa to a $100 mandatory
special assessment, a 42-month sentence, and three years of
supervised release for each of the three counts. The sentences
were to be served concurrently, and the supervised release
terms were to run concurrently. Zalapa also did not object to
the convictions or sentences when they were entered by the
district court.

   Zalapa now appeals his sentences and convictions for
Counts Two and Three. We have jurisdiction under 28 U.S.C.
§ 1291. Zalapa contends that, because the convictions and
sentences under 26 U.S.C. § 5861(d) are multiplicitous, they
violate the Double Jeopardy Clause. We agree.

   Zalapa alternatively argues that, even if he waived the mul-
tiplicity objection by failing to object to his convictions and
sentences below, he is still entitled to relief due to ineffective
assistance of counsel. For the reasons discussed below, we
decline to reach this alternate ground and instead reverse
based on the district court’s plain error in sentencing Zalapa
on the multiplicitous counts and entering judgment.

                         II.   Analysis

A.   Multiplicitous Convictions and Sentences

   [1] We conclude that Zalapa’s convictions and sentences on
the firearm counts are multiplicitous. Where a defendant is
convicted of multiple violations of the same statute based
upon a single act or transaction, “the Supreme Court has
stated that the proper inquiry involves the determination of
15968                  UNITED STATES v. ZALAPA
‘[w]hat Congress has made the allowable unit of prosecu-
tion.’ ” United States v. Keen, 

, 1118 (9th Cir.
1997) (quoting United States v. Universal C.I.T. Credit Corp.,

, 221 (1952)).1 We have recognized that “section
5861(d) expresses an unambiguous congressional intent to
make each firearm a unit of prosecution.” United States v.
Alverson, 

, 347 (9th Cir. 1982) (emphasis
added). Similarly, we have held that it was not Congress’s
intent to impose multiple punishments for possessing a single
firearm even if that firearm violates different subsections of
26 U.S.C. § 5861. See United States v. Edick, 

,
773-75 (9th Cir. 1979).

   [2] Accordingly, convicting and sentencing Zalapa for both
firearm counts resulted in multiplicitous sentences and con-
victions and violated the Double Jeopardy Clause.

B.    Waiver

   [3] We now address whether Zalapa waived his right to
challenge the multiplicitous convictions and sentences by fail-
ing to object below. We conclude that he did not. In reaching
that conclusion, we recognize the distinction between objec-
tions to multiplicity in the indictment, which can be waived,
and objections to multiplicitous sentences and convictions,
which cannot be waived. See United States v. Smith, 

, 1000 & n.4 (9th Cir. 2005) (“Multiplicity of sentences is
unlike the issue of multiplicity of an indictment which can be
waived if not raised below.”).
  1
    The convictions at issue here, both arising under the same statute, are
different from convictions for conduct punishable under two or more sepa-
rate statutes. Compare 

with Ball v. United States,

, 861 (1985). Multiplicity where the same conduct is pun-
ished under separate statutes requires application of the test set forth in
Blockburger v. United States, 

, 304 (1932), which permits
double punishment only where each charge requires proof of an element
not required by the other. 

. Because Zalapa’s convic-
tions for Counts Two and Three arose under the same statute, 26 U.S.C.
§ 5861(d), we do not apply the Blockburger test.
                    UNITED STATES v. ZALAPA                15969
   This conclusion is consistent with our holding in Launius
v. United States, 

(9th Cir. 1978). In that case,
we held that a defendant’s guilty plea to a multiplicitous
indictment did not constitute a waiver of the right to raise a
double jeopardy claim as to his multiplicitous convictions and
sentences. 

We also recognized that Rule 12 of
the Federal Rules of Criminal Procedure, the rule relating to
pretrial motions, “ ‘applies only to objections with regard to
the error in the indictment itself.’ ” 

(quoting United
States v. Rosenbarger, 

, 721-22 (6th Cir. 1976)).
We further recognized that even though “ ‘dismissal of a mul-
tiplicitous indictment is not required’ ” under Rule 12, “ ‘if
sentences are imposed on each count of that multiplicious
indictment the defendant is not forced to serve the erroneous
sentence because of any waiver.’ ” 

536 F.3d at 721-22.

   We recently reaffirmed this principle in United States v.
Ankeny, 

, 838-39 (9th Cir. 2007). In Ankeny, the
defendant did not object to a multiplicitous indictment before
pleading guilty. 

Instead, he moved to dismiss the
multiplicitous counts only after the district court accepted his
guilty plea. 

rejected the government’s argument
that Ankeny waived any objection to the form of the indict-
ment by failing to object before the district court accepted his
guilty plea. In holding that Ankeny need not have objected
before his guilty plea was accepted, the court observed that
“any objection to the indictment presumably would have been
overruled because the government still would have had the
opportunity to present proof of separate acquisition and pos-
session.” 

his objection at the appropriate
time” by moving to dismiss the multiplicitous counts prior to
sentencing. See 

then observed that “the plain error standard
applies when the defendant failed to raise the issue of multi-
plicitous sentences in the district court, which was not the
case here.” 

noted that “even if the plain error
15970               UNITED STATES v. ZALAPA
standard did apply, Defendant’s conviction of multiple counts
of being a felon in possession of a firearm, rather than a single
count, harmed his substantial rights . . . .” 

(internal
citations omitted).

   [4] Our case law distinguishing between objections to mul-
tiplicity in the indictment itself and objections to multiplicit-
ous convictions and sentences follows explicit Supreme Court
precedent. See Ball v. United States, 

, 859
(1985). In Ball, the Supreme Court held that the district court
has a duty to resolve multiplicitous charges only after the jury
returns a guilty verdict on the multiplicitous charges. 

“Should the jury return guilty verdicts for each [multipli-
citous] count, . . . the district judge should enter judgment on
only one of the statutory offenses.” 

argues that United States v. Klinger, 

, 708 (9th Cir. 1997), controls our decision in this
case. We disagree. Klinger dealt only with a challenge to the
multiplicitous form of the indictment and not with a challenge
to multiplicitous convictions and sentences based on double
jeopardy. In Klinger, consistent with our precedent on this
issue, we held that the defendant waived any challenge to the
form of a multiplicitous indictment by failing to object below.

see also United States v. Smith, 

,
1096 (9th Cir. 1989) (observing that “courts have addressed
under Rule 12(b)(2) such defenses as misnomer, duplicity or
multiplicity . . . and other defects in the indictment or infor-
mation that go to matters of form rather than substance”).

   [5] Here, like the defendants in the 2005 Smith decision,
Launius, and Ankeny, Zalapa challenges only his multiplicit-
ous convictions and sentences, not the form of the indictment.
Zalapa voluntarily pleaded guilty to all three counts and did
not object to the form of the indictment in the district court.
By failing to object to the multiplicitous indictment before
pleading guilty, Zalapa waived any objection to the form of
the indictment. 

. Zalapa did not, how-
                    UNITED STATES v. ZALAPA                 15971
ever, waive his right to object to his sentences and convictions
as multiplicitous on appeal. See 

;

& n.4.

C.   Plain Error

  We hold that it was plain error for the district court not to
vacate one of the firearm counts before entering judgment and
sentencing Zalapa.

   Where a defendant fails to raise the issue of multiplicity of
convictions and sentences before the district court, we review
the district court’s decision for plain error. See 

; 

. Under plain error
review, a defendant “must show (1) an error, (2) that is plain,
(3) that affects substantial rights, and (4) that seriously affects
the fairness, integrity, or public reputation of judicial proceed-
ings.” 

(citing Johnson v. United
States, 

, 467 (1997)).

   [6] “[A]n error is not plain unless it is ‘clear’ or ‘obvi-
ous.’ ” 

(quoting United States v.
Olano, 

, 734 (1993)). “Plain error is so clear-cut,
so obvious, a competent district judge should be able to avoid
it without benefit of objection.” 

marks
omitted). Because Zalapa’s convictions and sentences for
Counts Two and Three arose out of possession of a single
firearm and because our prior case law clearly describes Con-
gress’s intent to avoid imposing multiple punishments under
26 U.S.C. § 5861 for possessing a single firearm, the district
court plainly erred when it entered judgment and sentenced
Zalapa on both firearm counts. See 

;

.

  [7] The multiplicitous convictions and sentences affect
Zalapa’s substantial rights because they have collateral conse-
quences, including the possibility of an increased sentence
under a recidivist statute for a future offense. See Ball, 470
15972                  UNITED STATES v. ZALAPA
U.S. at 864-65; Rutledge v. United States, 

, 301-
03 (1996). Each conviction also carried with it a mandatory
$100 special assessment, which constitutes additional punish-
ment that would not have been imposed absent the multiplicit-
ous conviction and sentence. See 

-
03. Imposition of an erroneously-imposed sentence, even a
concurrent sentence, can have significant collateral conse-
quences that we cannot foretell at the time of decision. See
Guam v. Torre, 

, 1180 (9th Cir. 1995) (quoting

) (“The law is plain that multiple con-
victions, apart from concurrent sentences, carry ‘adverse col-
lateral consequences that may not be ignored.’ ”); see also
United States v. Kincaid, 

, 112 (9th Cir. 1990)
(noting that although neither the defendant nor the court could
“identify a specific prejudice which may stem from his erro-
neous sentence, we are unwilling to place upon [the defen-
dant] the risk that such a prejudice will manifest itself in the
future”). These collateral consequences affect Zalapa’s sub-
stantial rights and therefore justify vacating the multiplicitous
conviction and sentence.2

   [8] Finally, the district court’s error was serious enough to
“ ‘affect[ ] the fairness, integrity or public reputation of judi-
cial proceedings.’ ” See 

(quoting
United States v. Young, 

, 15 (1985)). Because the
multiplicitous convictions and sentences carry with them sig-
nificant potential for collateral consequences, we conclude
that the district court’s error seriously affected the fairness of
the judicial proceedings. By convicting and sentencing Zalapa
on both firearm counts, the district court’s plain error exposed
Zalapa to double jeopardy, which makes his convictions fun-
damentally unfair.
  2
   The government argues that any adverse collateral consequences result
from Zalapa’s convictions, and not his sentences, and that he waived any
challenge to the convictions by failing to object to the indictment. Rut-
ledge drew no such distinction in vacating one of the defendant’s sen-
tences and convictions despite his not objecting at trial, and we decline to
do so. 

, 307.
                    UNITED STATES v. ZALAPA                15973
                       III.   Conclusion

   [9] In summary, we conclude that Counts Two and Three
are multiplicitous. The remedy for meritorious multiplicity
claims is for the district court to vacate the multiplicitous con-
viction and sentence. See 

; 

. In accordance with Ball, we therefore remand to
the district court with instructions to vacate the multiplicitous
conviction, sentence, and $100 mandatory special assessment
for one of the two counts under 26 U.S.C. § 5861(d).

  REVERSED AND REMANDED