Aspect-Oriented Programming has introduced new types of software faults that may be systematically tackled with mutation testing. However, such testing approach requires adequate tooling support in order to be properly performed. This paper addresses this issue, introducing a novel tool named Proteum/AJ. Proteum/AJ realises a set of requirements for mutation-based testing tools and overcomes some limitations identified in previous tools for aspect-oriented programs. Through an example, we show how Proteum/AJ was designed to support the main steps of mutation testing. This preliminary use of the tool in a full test cycle provided evidences of the feasibility of using it in real software development processes and helped us to reason about the current functionalities and to identify future needs.