Work based assessment (WBA) is a common but contentious practice increasingly used to grade university students on professional degrees. A key issue in WBA is the potentially low assessment literacy of the assessors, which can lead to a host of unintended results, including grade inflation. We identified grade inflation in the WBA of the clinical module analysed for this study, and to address it we trialled two adjustments over a four-year period. The first and simpler adjustment, reducing the academic weighting of the WBA component of the module, appeared to lower grade inflation but actually had the inverse effect over time. The second adjustment, introducing a structured formative assessment, reduced the average WBA grade both initially and over time. In addition to this desired result, the second adjustment has brought ongoing benefits to the learning and teaching on the module as a whole.