Expansion of the autophagosomal membrane requires a mechanism to supply lipids while excluding most membrane proteins. In this issue, Valverde et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201811139) identify ATG2, a member of the autophagy-related protein family, as a lipid transfer protein and provide important novel insights on how autophagosomes grow.