@martijnhoekstra are you thinking of a drop-in replacement artifact that could be used instead of the standard library? The problem I see with this idea is that sbt would have to know about it, so that the replacement artifact “wins” over the 2.13 standard library in dependency resolution if both are pulled into the dependency graph. So we’re back to the issue described in the original post: if some of your dependencies brings in the replacement artifact, you need to be using an up-to-date version of sbt (that doesn’t exist at this point), otherwise things break. (I assume there’s no way to make this work with current sbt releases.)