diff --git a/impls/src/backends/lmdb.rs b/impls/src/backends/lmdb.rs
index c7e6808..178e90d 100644
--- a/impls/src/backends/lmdb.rs
+++ b/impls/src/backends/lmdb.rs
@@ -16,7 +16,7 @@ use std::cell::RefCell;
 use std::{fs, path};
 
 // for writing stored transaction files
-use byteorder::BigEndian;
+use byteorder::{BigEndian, WriteBytesExt};
 use std::fs::File;
 use std::io::{Read, Write};
 use std::marker::PhantomData;
@@ -40,7 +40,6 @@ use crate::util::{self, secp, ToHex};
 
 use rand::rngs::mock::StepRng;
 use rand::thread_rng;
-use tokio::io::AsyncWriteExt;
 
 pub const DB_DIR: &str = "db";
 pub const TX_SAVE_DIR: &str = "saved_txs";
@@ -775,6 +774,6 @@ where
 /// Build a db key from a byte vector identifier and numeric identifier
 fn to_key_u64<K: AsRef<[u8]>>(k: K, val: u64) -> Vec<u8> {
 	let mut res = k.as_ref().to_vec();
-	res.write_u64(val);
+	res.write_u64::<BigEndian>(val).unwrap();
 	res
 }