Our past research suggests, surprisingly, that people who tell lies are sometimes perceived as more credible than people who provide false information because they are mixed up. We tested perceived competence as one mechanism that drives liars' credibility advantage: Liars might appear more competent than mixed-up people because they must keep track of their stories to lie about details. Using a between-subjects design, 282 university students responded to vignettes about witnesses who either strategically lied or mixed up information while testifying about a car accident. Crossed with this factor, witnesses were described as either highly competent or highly incompetent. Whereas prior work using similar vignettes found that liars were more credible than mixed-up witnesses, in the current study, liars' credibility advantage disappeared after equating competence across lying and mixed-up witnesses. These results suggest that perceived competence explains part of strategic liars' credibility advantage.