Math courses graded on homework, tests, and a final examination can result in students putting together enough partial credit to pass the class without gaining a reasonable mastery of the course content. Mastery-based testing can help to address this by allowing the instructor to align course grades with mastery of the learning objectives for the course. This article is a reflection on my experiences implementing mastery-based testing in Discrete Mathematics. I give a brief introduction to the ideas behind mastery-based testing and discuss the construction of two of my mastery tests. The change affected my teaching, helping me to see where students need help understanding the material. Instructor observation and feedback from student evaluations of instruction indicate that student learning was improved with the change.