diff --git a/src/assignments/assignment08.rs b/src/assignments/assignment08.rs
index a4f12c3..972b1d3 100644
--- a/src/assignments/assignment08.rs
+++ b/src/assignments/assignment08.rs
@@ -8,7 +8,7 @@
 /// Returns an anonymous function that applies the given function `f` for `n` times.
 ///
 /// For instance, `repeat(3, f)(x)` roughly translates to `f(f(f(x)))`.
-pub fn repeat<T, F: FnMut(T) -> T>(n: usize, f: F) -> impl FnMut(T) -> T {
+pub fn repeat<T, F: FnMut(T) -> T>(n: usize, mut f: F) -> impl FnMut(T) -> T {
     todo!();
     f // This line has been added to prevent compile error. You can erase this line.
 }
diff --git a/src/assignments/mod.rs b/src/assignments/mod.rs
index 07197ef..3589351 100644
--- a/src/assignments/mod.rs
+++ b/src/assignments/mod.rs
@@ -1,6 +1,7 @@
 //! KAIST CS220 Assignments.
 
 #![allow(dead_code)]
+#![allow(unused_mut)]
 #![allow(unreachable_code)]
 #![allow(unused_variables)]