Crate not building with minimal-versions of dependencies

This crate builds fine normally, but it does not build when downgrading all dependencies as far as their semver spec allows:

$ cargo +nightly update -Z minimal-versions && cargo build
    Updating crates.io index
   Compiling err-derive v0.3.0 (/home/faern/src/thirdparty/err-derive)
error: no rules expected the token `#`
   --> src/lib.rs:155:59
    |
155 | decl_derive!([Error, attributes(error, source, cause)] => #[proc_macro_error] error_derive);
    |                                                           ^ no rules expected this token in macro call

warning: unused import: `proc_macro_error`
   --> src/lib.rs:152:31
    |
152 | use proc_macro_error::{abort, proc_macro_error};
    |                               ^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(unused_imports)]` on by default

warning: `err-derive` (lib) generated 1 warning
error: could not compile `err-derive` due to previous error; 1 warning emitted

I have not yet checked exactly which crate needs a stricter semver bound to which version. But I wanted to report it.