Timothy Searchinger suggests that biofuel production must generate ‘additional carbon’ in order to reduce emissions, and that when biofuels use existing cropland they use crops which would have grown anyway, and the direct carbon uptake is therefore not additional. Such biofuels will only achieve a carbon benefit if they increase carbon uptake indirectly, e.g. through raising market prices and incentivising farmers to grow more crops elsewhere. A further point is that whether biofuels indirectly increase net carbon uptake is uncertain, for all the same reasons that quantifying indirect land use change (ILUC) is uncertain. We provide an example to show that an important part of Searchinger’s argument is flawed, i.e. it is possible for biofuels grown on existing cropland to create direct GHG reductions. One of Searchinger’s conclusions, that the net benefits of biofuels are uncertain, is still correct. However, this is not a new conclusion, and stems from the fact that quantifying ILUC is uncertain, which we already knew.