The cognitive failures questionnaire (CFQ) measures the self-reported frequency of everyday mistakes and represents the tendency to make everyday mistakes. The present research pursues an alternative interpretation of the CFQ namely the tendency to evaluate one's worth and functioning in a pessimistic way. Study 1 shows that the self-reported frequency of daily mistakes is related to a pessimistic self-evaluation of task performance. Study 2 shows that CFQ has considerable overlap with a construct that represents the self-evaluation of one's general worth and functioning, namely core self-evaluations. It is discussed what these results mean for the applicability of the cognitive failures questionnaire as an indication of the tendency to make mistakes.