`funelim` with dependently typed function doesn't eliminate

[Lysxia]

In the following I expected f n to be rewritten by funelim (f n), but it only changes n.

From Equations Require Import Equations.

Set Implicit Arguments.
Set Contextual Implicit.

Inductive N : nat -> Type :=
| NS y : N (S y) -> N y
.

Equations f : forall n, N n -> N n :=
  f (NS n) := NS (f n).

Lemma foo x (n : N x) : f n = n.
Proof.
 funelim (f n).