The High Seas Treaty, formally known as the Agreement under the United Nations Convention on the Law of the Sea on the Conservation and Sustainable Use of Marine Biological Diversity of Areas beyond National Jurisdiction (BBNJ Agreement), is set to hold its first Conference of the Parties (COP1) in January 2027 (1). The treaty’s preamble names plastic pollution among the pressures that it responds to, yet none of its four mechanisms—marine protected areas, environmental impact assessments (EIAs), capacity-building and technology transfer, and marine genetic resources management—addresses it (1). COP1 can close this gap, without taking on a new mandate, by making plastics an explicit consideration in two areas already on its agenda: incorporating it into how the clearing-house mechanism (CHM) will operate and into the mandate of the scientific and technical body (STB), which will shape the treaty’s science-based rules.