JOHN K. BUSH, Circuit Judge. Before us are two appeals that arise from the same intellectual-property dispute. Relevant to both, the testing company ACT, Inc. (“ACT”) asserts that its former-partner-turned-competitor, Worldwide Interactive Network, Inc. (“WIN”), infringed ACT’s copyright in its “Skill Definitions.” Skill Definitions are, in essence, descriptions of the various workplace skills that ACT intends to test with its career-readiness assessments. ACT markets those assessments to schools, workplaces, and state departments of education.

After the parties’ relationship soured, WIN began to market its own career-readiness assessments that purported to test various “Learning Objectives”—descriptions of workplace skills suspiciously similar to ACT’s Skill Definitions. In response, ACT filed suit. The district court awarded partial summary judgment to ACT on its copyright-infringement claims and later preliminarily enjoined WIN from continued infringement. WIN’s first appeal concerns the imposition (and scope) of that preliminary injunction. Finding WIN’s objections unpersuasive, however, we affirm.

We then turn to WIN’s second appeal, which concerns a distinct but related issue. After WIN began to infringe ACT’s Skill Definitions once again with a set of “revised” Learning Objectives, the district court ordered ACT to amend its complaint with new allegations that the revised Learning Objectives are likewise infringing. In response to the amended complaint, WIN filed an amended answer asserting a never-before-offered defense: that because WIN designed the Learning Objectives to bid on various state contracts, it was entitled to assert those states’ sovereign immunity from the copyright claims—so-called “derivative sovereign immunity.” See Am. Answer ¶¶242–44, R. 551. But the district court struck the new defense as both untimely and “frivolous.” Relying on the timeliness ground alone, we affirm that decision as well.