A general court-martial composed of officer members convicted appellant, contrary to his pleas, of larceny of military property of the United States (2 specifications) and submitting a false and fraudulent claim for temporary duty expenses, in violation of Articles 121 and 132, Uniform Code of Military Justice, 10 USC §§ 921 and 932, respectively. Appellant pleaded guilty to submitting a false and fraudulent claim for dependent travel expenses and violating a lawful general regulation, in violation of Articles 132 and 92, UCMJ, 10 USC §§ 932 and 892, respectively. The adjudged and approved sentence provides for a bad-conduct discharge and reduc*270tion to the lowest enlisted grade. In a divided opinion, the Court of Criminal Appeals affirmed the findings and sentence. Our Court granted review of the following issue:
WHETHER THE MILITARY JUDGE ERRED TO THE SUBSTANTIAL PREJUDICE OF APPELLANT BY DENYING A DEFENSE MOTION TO REQUIRE A PREFERRAL OF CHARGES AFTER A MAJOR CHANGE TO SPECIFICATIONS 1-4 OF CHARGE I.1
When the charges were preferred, specifications 1 through 4 of Charge I alleged that appellant stole “property of the United States Air Force.” Based on the Article 322 Investigating Officer’s recommendation, the specifications were amended before trial by adding an allegation that the property was “military property,” but the charge and specifications were not preferred or investigated anew. The effect of the amendment was to increase the maximum confinement for specifications 1, 3, and 4 from 5 years to 10 years and for specification 2 from 6 months to 1 year. See para. 46e(l), Part IV, Manual for Courts-Martial, United States (1994 ed.), which was in effect at the time of appellant’s offenses.
At trial, appellant made a timely motion to dismiss the four specifications of larceny on the ground that the amendment adding the words “military property” was a major change, requiring that the amended specifications be preferred anew. The military judge denied the motion. He correctly noted that the amendment did not add an offense or mislead the accused. He correctly focused on the issue whether the allegation that the property was “military property” added a “substantial matter.” The military judge also correctly noted that the allegation of “military property” did not add an element of an offense but instead added a sentence escalator. Relying on this Court’s opinion in United States v. Sullivan, 42 MJ 360 (1995), and the Eighth Circuit opinion in Wright v. Lockhart, 854 F.2d 309 (8th Cir.1988), the military judge ruled that adding the sentence escalator was not a “substantial matter.” We hold that the military judge’s interpretation of “substantial matter” was erroneous.
RCM 603(c), Manual, supra, permits “minor” amendments of charges and specifications “at any time before findings are announced if no substantial right of the accused is prejudiced.” RCM 603(a) defines minor changes as “any except those which add a party, offenses, or substantial matter not fairly included in those previously preferred, or which are likely to mislead the accused as to the offenses charged.” RCM 603(d) provides that major changes “may not be made over the objection of the accused unless the charge or specification affected is preferred anew.”
This Court’s opinion in United States v. Sullivan, supra, is relevant but not controlling. In Sullivan, the amendment changed the offense to a lesser-included offense with a lesser punishment. Under those circumstances, we held that the amendment was minor.
Wright v. Lockhart, supra, was decided on the basis of Fed.R.Crim.P. 7(e). RCM 603(c) is based on Fed.R.Crim.P. 7(e). Sullivan, 42 MJ at 364-65, citing Drafters’ Analysis of RCM 603, Manual, supra at A21-30. Nevertheless, there are some significant differences between RCM 603 and Fed.R.Crim.P. 7(e). Fed.R.Crim.P. 7(e) permits amendment “if no additional or different offense is charged and if substantial rights of the defendant are not prejudiced.” RCM 603(a) is broader, treating changes as major if they “add a party, offenses, or substantial matter not fairly included in those previously preferred.” Fed.R.Crim.P. 7(e) makes no reference to “substantial matter.”
*271We hold that adding the sentence escalator that doubled the punishment was a “substantial matter” within the meaning of RCM 603(a). See United States v. Krutsinger, 15 USCMA 235, 35 CMR 207 (1965) (amendment aggravating the seriousness of the offense and subjecting accused to greater punishment was improper). Thus, we hold that the Air Force court erred when it held that the amendment was “minor.”
We are satisfied, however, that appellant was not prejudiced. He was not surprised by the amendment or hindered in his preparation for trial. Appellant received no confinement, negating any possibility that the increased maximum sentence caused him to receive a sentence to a longer term of confinement than would have been imposed absent the error. Appellant was sentenced to a bad-conduct discharge, even though a dishonorable discharge was authorized. In light of the seriousness of the offenses of which he was convicted, we believe that there is no reasonable likelihood that appellant would not have been sentenced to a punitive discharge, even if the stolen property had not been described as “military property.” Thus, we can say, “with fair assurance, ... that the judgment was not substantially swayed by the error.” Kotteakos v. United States, 328 U.S. 750, 765, 66 S.Ct. 1239, 90 L.Ed. 1557 (1946).
The decision of the United States Air Force Court of Criminal Appeals is affirmed.
Judge EFFRON did not participate. See 48 MJ 317 (1997).. We also granted review of an issue whether the application of Articles 57(a) and 58b, UCMJ, to appellant’s case violates the Ex Post Facto Clause of the United States Constitution. Because one of appellant’s offenses was committed after April 1, 1996, and is punishable by a dishonorable discharge, total forfeitures, confinement for 5 years, and reduction to the lowest enlisted grade, the Ex Post Facto Clause was not violated. See United States v. Carter, No. 97-1121, — MJ — (Daily Journal Aug. 20, 1998).
. Uniform Code of Military Justice, 10 USC § 832.