SUMMARY ORDER

Plaintiffs-Appellants Wadena Pyatt and Bang Hitz Publishing appeal from a judgment of the United States District Court for the Southern District of New York *24 (McMahon, /.), dismissing their complaint pursuant to Rule 12(b)(6). We assume the parties’ familiarity with the underlying facts and procedural history.

We review de novo a district court’s dismissal pursuant to a Rule 12(b)(6) motion. In this case, we affirm for the well-stated reasons of the court below. The originally registered copyrights and Usher’s “Caught Up” have little in common beyond the title and the phrase “Caught Up.” The songs are lyrically and musically distinct and the district court correctly concluded that the claim failed the ordinary observer test. See Yurman Design, Inc. v. PAJ, Inc., 262 F.3d 101, 111 fn. 3 (2d Cir. 2001).

We also affirm because we agree with the district court’s interpretation of the complaint as alleging copyright infringement only with respect to the originally copyrighted works. Appellants contend the district court misconstrued the complaint when it held that the subsequently registered works (those registered after filing of the complaint and after Defendants’ motions to dismiss were filed) were incorporated in Appellants’ copyright infringement claims. The complaint’s broad references to “materials,” “works,” and “versions” are simply insufficient to bring post-complaint registrations within the scope of the complaint’s allegations. This is so especially because the “Copyright Act ... requires copyright holders to register their works before suing for copyright infringement.” Reed Elsevier, Inc. v. Muchnick, — U.S. -, -, 130 S.Ct. 1237, 1241, 176 L.Ed.2d 18 (2010) (citing 17 U.S.C. § 411(a)).

Appellants claim that the court, in interpreting the complaint, should have considered certain documents that Appellants attached to their opposition to Defendants’ motions to dismiss. These documents (lyric sheets and expert reports regarding subsequently registered works) were not attached to or integrated into the complaint, or incorporated therein. The district court did not err by declining to examine them. See DiFolco v. MSNBC Cable LLC, 622 F.3d 104, 111 (2d Cir. 2010).

Finally, we affirm the district court’s denial of Appellants’ motion for leave to amend the complaint. We review de novo denials of motions to amend based on a determination that amendment would be futile. Hutchison v. Deutsche Bank Sec. Inc., 647 F.3d 479, 490 (2d Cir. 2011). Amendment under rule 15(a) was futile in this case because only an allegation that Defendants infringed on Appellants’ newly-registered copyrights could have potentially allowed Appellants to state a claim for relief. Appellants’ proposed amended complaint failed to allege these new copyrights and Appellants did not move for leave to file a supplemental pleading, see Fed.R.Civ.P. 15(d). In the face of this inaction, the district court had no duty to order sua sponte further amendment or supplementation.

For the foregoing reasons, the judgment of the district court is hereby AFFIRMED.