Child marriage is associated with adverse outcomes related to women's well-being. Many countries have introduced laws banning this practice, and a number of studies have evaluated their impact. Scant research has focused on instances where countries have lowered the legal minimum age at marriage, even though such 'reverse policies' could result in stalled or uneven progress in eradicating child marriage. Using visualization techniques, regression analyses, and multiple robustness checks, we document changes in the prevalence of child marriage in Mali, where in 2011 the general minimum age at marriage of 18 was lowered to 16. Since 2011, the prevalence of child marriage has progressively increased among women with no education and women living in communities characterized by low local development. We reflect on the role that data collection processes may play in explaining some of these findings and stress how repealing existing provisions aiming to protect girls can have adverse consequences on the most vulnerable social strata.