The present study describes the effects of product platform changes on lean production systems. Current research into product platforms focuses mostly on the development stage. However, although the initial development of platforms is an important issue, product platforms often evolve during later stages due to emerging engineering changes. The research question for this study is: how do firms manage the impact of changes on lean production systems, and what is the role of product platforms in stabilising the resulting variety during production and use? The study illustrates the fundamental impact of changes in the platform on procurement, manufacturing, and maintenance. Based on a case study, several important requirements in the management of platform changes are identified. Firstly, platform change attributes should be clearly defined because they determine the state of the platform during its lifecycle. Further, product platform lifecycle management (PPLM) is required to support impact analysis during a platform's lifecycle. Finally, configuration management of the product base installed in the field is required. Throughout the company, data management concerning versions, variants, and changes of platform attributes has to be organised. Further research should focus on defining the attributes of a platform more precisely and, subsequently, should concentrate on the development of a change or freeze policy based on these attributes.