Async method taking a reference argument fails to compile

[Wesmania]

I have this minimal example:

#[cfg(test)]
use mocktopus::macros::*;
pub struct Foo { }
#[cfg_attr(test, mockable)]
impl Foo {
    pub async fn read(&mut self, buf: &mut[u8]) {
        let _ = buf;
    }
}

It builds fine without tests, but fails with tests enabled with:

error[E0621]: explicit lifetime required in the type of `buf`
  --> src/main.rs:13:5
   |
12 |       pub async fn read(&mut self, buf: &mut[u8]) -> ()
   |                                         -------- help: add explicit lifetime `'mocktopus` to the type of `buf`: `&'mocktopus mut [u8]`
13 | /     {
14 | |         let _ = buf;
15 | |     }
   | |_____^ lifetime `'mocktopus` required

Using pub async fn read<'a>(&mut self, buf: &'a mut[u8]) instead silences the error. I have no idea if it's a good workaround.