Rust SDL2 Timer: How can I return timer object from the function?

I am using sdl2 crate and I am trying to create a simple "context" object with timer inside of it. I have the following code

extern crate sdl2;

struct Ctx<'a, 'b> {
    timer: sdl2::timer::Timer<'a, 'b>,
}

impl<'a,'b> Ctx<'a, 'b> {
    pub fn new() -> Ctx<'a,'b> {
        let sdl_context = sdl2::init().unwrap();
        let timer_subsystem = sdl_context.timer().unwrap();
        let timer = timer_subsystem.add_timer(100, Box::new(|| -> u32 { 100 }));

        Ctx { timer }
    }
}

pub fn main() {
    let _ = Ctx::new();
}

The problem is that add_timer() seem to borrow timer_subsystem object, and it prevents timer to be moved out of the function.

error[E0515]: cannot return value referencing local variable `timer_subsystem`
  --> src/main.rs:13:9
   |
11 |         let timer = timer_subsystem.add_timer(100, Box::new(|| -> u32 { 100 }));
   |                     ----------------------------------------------------------- `timer_subsystem` is borrowed here
12 |
13 |         Ctx { timer }
   |         ^^^^^^^^^^^^^ returns a value referencing data owned by the current function

However, if I look into add_timer(), I cannot see why does the reference is considered still alive. In fact the self reference is not used in the function at all: https://docs.rs/sdl2/latest/src/sdl2/timer.rs.html#17-32

    pub fn add_timer<'b, 'c>(&'b self, delay: u32, callback: TimerCallback<'c>) -> Timer<'b, 'c> {
        unsafe {
            let callback = Box::new(callback);
            let timer_id = sys::SDL_AddTimer(
                delay,
                Some(c_timer_callback),
                mem::transmute_copy(&callback),
            );

            Timer {
                callback: Some(callback),
                raw: timer_id,
                _marker: PhantomData,
            }
        }
    }

I was trying to put both timer and timer_subsystem to Ctx (to make sure their lifetime is the same), but it didn't help. Neither wrapping them with Box<> (to prevent having a dangling pointer after timer_subsystem was moved), but neither worked.

Why of I have a reference to local data here and how can I properly return the timer object?