diff --git a/src/fuzzing.rs b/src/fuzzing.rs
index 85634430c..ad920b9ab 100644
--- a/src/fuzzing.rs
+++ b/src/fuzzing.rs
@@ -1,8 +1,12 @@
+//! # Fuzzing module.
+//!
+//! This module exposes private APIs for fuzzing.
+
 /// Fuzzing target for simplify().
 ///
 /// Calls simplify() and panics if simplify() panics.
 /// Does not return any vaule to avoid exposing internal crate types.
 #[cfg(fuzzing)]
-pub fn simplify(mut input: String, is_chat_message: bool) {
+pub fn simplify(input: String, is_chat_message: bool) {
     crate::simplify::simplify(input, is_chat_message);
 }