In order to support users to recover from erroneous changes or to explore pre- viously executed modifications, collaborative editing systems offer the undo mechanism. Providing an undo feature in fully decentralised collaborative editors is challenging as users are allowed to revert any changes performed by any user. Operational transformation has been devised as a suitable mechanism for maintaining consistency in collaborative editing systems. Therefore, in this paper we present a novel undo approach in the context of oper- ational transformation mechanism. Our approach is based on the notion of compensation used in databases where compensating operations semantically undo other operations. Moreover, our compensation mechanism is less restraining than any undo approaches and is generic in the sense that it can be used in association with any operational transformation algorithm.