diff --git a/src/db/cow/mod.rs b/src/db/cow/mod.rs
index b646da5..5998939 100644
--- a/src/db/cow/mod.rs
+++ b/src/db/cow/mod.rs
@@ -18,7 +18,7 @@ use revm::{
 /// [`CacheDB`]: revm::database::in_memory_db::CacheDB
 /// [`State`]: revm::database::State
 /// [`ConcurrentState`]: crate::db::sync::ConcurrentState
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct CacheOnWrite<Db> {
     cache: Cache,
     inner: Db,
diff --git a/src/db/sync/child.rs b/src/db/sync/child.rs
deleted file mode 100644
index 8b13789..0000000
--- a/src/db/sync/child.rs
+++ /dev/null
@@ -1 +0,0 @@
-