diff --git a/src/protocol/arena.rs b/src/protocol/arena.rs
index 6afdc88e49dc4a56b392a9dc204d7a664cb8713d..ad304d8fdc5201e607e27ce500ae1e384966d67f 100644
--- a/src/protocol/arena.rs
+++ b/src/protocol/arena.rs
@@ -1,4 +1,5 @@
-use crate::common::*;
+use std::fmt::{Debug, Formatter};
+
 use core::hash::Hash;
 use core::marker::PhantomData;