diff --git a/crates/api_server/src/impls/zkos.rs b/crates/api_server/src/impls/zkos.rs
index 48c719de..ffc2a69c 100644
--- a/crates/api_server/src/impls/zkos.rs
+++ b/crates/api_server/src/impls/zkos.rs
@@ -14,6 +14,6 @@ impl ZKOSNamespace {
 #[async_trait]
 impl ZKOSNamespaceServer for ZKOSNamespace {
     async fn get_witness(&self, batch: u32) -> RpcResult<Option<String>> {
-        Ok(zkos_get_batch_witness(&batch).map(|data| hex::encode(data)))
+        Ok(zkos_get_batch_witness(&batch).map(hex::encode))
     }
 }