Although human centered design (HCD) is a foundational approach in a wide range of fields, sometimes HCD can lead to “designed injustice” – where products or systems facilitate unjust outcomes in society. Here, we present a new method, the persona multiplication method (PMM), which helps designers avoid some of the dangers implicit in traditional HCD. From a practical perspective, PMM helps guide designers through an evaluation of the implicit or potential designed injustice early in the design process. Our approach is grounded in traditional HCD methods as currently applied across a wide range of fields, including Product Design (PD), Human Factors Engineering (HFE), User Experience Design (UX), and Human Computer Interaction (HCI). PMM involves adding a new “multiplication and evaluation” step in the design process – just before leaving the persona-development phase. Through a series of case studies, we demonstrate how the method can be applied across a range of design domains. We hope to inspire further development of additional tools, methods, systems, and processes to help ensure “designed injustice” occurs less frequently over time.