can't find crate for `alloc`

[l3gacyb3ta]

I'm trying to build one of the demos, but it keeps giving me an issue with building it?

error[E0463]: can't find crate for `alloc`
  --> src/main.rs:13:1
   |
13 | psx::sys_heap!(4 kb);
   | ^^^^^^^^^^^^^^^^^^^^ can't find crate
   |
   = note: this error originates in the macro `$crate::sys_heap` which comes from the expansion of the macro `psx::sys_heap` (in Nightly builds, run with -Z macro-backtrace for more info)