Software maintenance is a key activity in software development requiring considerable effort and time. Hence, it is important to increase the efficiency and effectiveness of the maintenance process. The objective of this article is to introduce a palette of indicators to assess the maintenance process based on indicators lean indicators. Four indicators aiming at detecting waste have been proposed, namely the inflow of maintenance requests, the flow of maintenance requests through the maintenance process with regard to continuous value creation and high throughput, the analysis of lead-times, and the analysis of workload. The research method is case study in which the proposed indicators were applied on the maintenance process of one case company (Ericsson AB).