Most of us believe that it would be unjust to act with indifference about the plight of future generations. Zipper arguments in intergenerational justice aim to show that we have duties of justice regarding future generations, regardless of whether we have duties of justice to future generations. By doing so, such arguments circumvent the foundational challenges that come with theorising duties to remote future generations, which result from the non-existence, non-identity and non-contemporaneity of future generations. I argue that zipper arguments (...) face several significant challenges. The ought-implies-can challenge points out that because prior generations determine what later generations can transfer, they determine how much they ought to transfer. In addition, both intentional and non-intentional non-compliance can break the chain of duties towards future generations on which zipper arguments rely. Some versions are surprisingly resilient especially in real-world circumstances. This paper does not show that zipper arguments inevitably fail, but all ways forward come at significant theoretical costs. Unless the challenges posed here are met (or shown as irrelevant), theorists of justice cannot side-track the foundational challenges that come with doing intergenerational justice. (shrink)