I added in staging.nix:
```
pkgsStaticGlibc = nixpkgsFun ({
      overlays = [ (self': super': {
        pkgsStaticGlibc = super';
      })] ++ overlays;
      crossOverlays = [ (import ./static.nix) ];
    } // lib.optionalAttrs stdenv.hostPlatform.isLinux {
      crossSystem = {
        isStatic = true;
        parsed = stdenv.hostPlatform.parsed;
      };
    });
```
...but that didn't seem to work