As momentum builds behind hugely ambitious initiatives like the Global Biodiversity Framework (GBF) 30 x 30 target and the European Union’s (EU’s) Biodiversity and Forestry Strategies, there is a danger that hard-won local conservation gains will be dissipated through leakage, the displacement of human activities that harm biodiversity away from the site of an intervention to other places. These off-site damages may be less than on-site gains—in which case the action is still beneficial but less so than it superficially seems. However, if activities are displaced to more biodiverse (or less productive) places, leakage impacts may exceed local benefits, so that well-intentioned efforts cause net harm. There is a pressing need for leakage effects like this to be acknowledged and as far as possible avoided or mitigated—through demand reduction, careful selection of conservation or restoration sites, or compensatory increases in production in lower-impact areas.