Conditional promises such as my promise to donate to Oxfam, if you donate to Oxfam, can only be broken if the condition event is realized. In this case, the condition event would be you giving money to Oxfam. At that point, if I do not give any money to Oxfam, I have broken my promise. Breaking one’s promises is [pro tanto] wrong. In the past I have argued that we can learn a good deal about the practice of promising by looking at failures of the practice, such as promise breaking. However, there are at least two other ways in which promises can be undercut. Besides breaking a promise a person might work to void a promise. In this paper I would like to look at what it is to void a promise, and whether or not it is morally wrong to void a promise in the same way as it is to break a promise. The answer will be that it is not. This will also have implications for what makes a promise insincere. I will also look at another way a promissory interaction can be undermined, by leaving a promise unactivated.