An algorithm for detecting sudden jumps in measured F0, which are likely to be inaccurate measures, is introduced. The method computes sample-to-sample differences in F0 and, based on a user-defined threshold, determines whether a difference is larger than naturally produced F0 velocities, thus, flagging it as an error. Various parameter settings are evaluated on a corpus of 30 American English speakers producing different intonational patterns, for which F0 tracking errors were manually checked. The paper concludes in recommending settings for the algorithm and ways in which it can be used to facilitate analyses of F0 in speech research.