One promise of electronic medical records (EMRs) was to reduce medication errors. That may not have occurred since one type of error, illegible orders, has been replaced by another: Order sets may incorrectly match a patient and necessary treatments. In this JAMA Performance Improvement podcast, we review a case in which guideline-based care was incorporated into an order set, then the guideline changed but the order set did not, resulting in a post-STEMI patient receiving β-blockers when they were contraindicated. Interviewees included Arjun Gupta, MD, University of Texas Southwestern Medical Center, and Jennifer L. Rabaglia, MD, MSc, Parkland Health and Hospital System, Dallas, Texas. Learning Objectives: To understand the role of β-blocker treatment in patients with acute myocardial infarction; to understand how EMR order sets should be developed and maintained. https://jamanetwork.com/journals/jama/fullarticle/10.1001/jama.2018.0845