diff --git a/util/src/overlaydb.rs b/util/src/overlaydb.rs
index 7c9b6b04b..8166dd318 100644
--- a/util/src/overlaydb.rs
+++ b/util/src/overlaydb.rs
@@ -26,7 +26,7 @@ use std::ops::*;
 use std::sync::*;
 use std::env;
 use std::collections::HashMap;
-use kvdb::{Database};
+use kvdb::{Database, DBTransaction};
 
 /// Implementation of the HashDB trait for a disk-backed database with a memory overlay.
 ///
@@ -36,7 +36,7 @@ use kvdb::{Database};
 ///
 /// `lookup()` and `contains()` maintain normal behaviour - all `insert()` and `remove()` 
 /// queries have an immediate effect in terms of these functions.
-//#[derive(Clone)]
+#[derive(Clone)]
 pub struct OverlayDB {
 	overlay: MemoryDB,
 	backing: Arc<Database>,
@@ -58,6 +58,36 @@ impl OverlayDB {
 		Self::new(Database::open_default(dir.to_str().unwrap()).unwrap())
 	}
 
+	/// Commit all operations to given batch.
+	pub fn commit_to_batch(&mut self, batch: &DBTransaction) -> Result<u32, UtilError> {
+		let mut ret = 0u32;
+		let mut deletes = 0usize;
+		for i in self.overlay.drain().into_iter() {
+			let (key, (value, rc)) = i;
+			if rc != 0 {
+				match self.payload(&key) {
+					Some(x) => {
+						let (back_value, back_rc) = x;
+						let total_rc: i32 = back_rc as i32 + rc;
+						if total_rc < 0 {
+							return Err(From::from(BaseDataError::NegativelyReferencedHash));
+						}
+						deletes += if self.put_payload(batch, &key, (back_value, total_rc as u32)) {1} else {0};
+					}
+					None => {
+						if rc < 0 {
+							return Err(From::from(BaseDataError::NegativelyReferencedHash));
+						}
+						self.put_payload(batch, &key, (value, rc as u32));
+					}
+				};
+				ret += 1;
+			}
+		}
+		trace!("OverlayDB::commit() deleted {} nodes", deletes);
+		Ok(ret)
+	}
+
 	/// Commit all memory operations to the backing database.
 	///
 	/// Returns either an error or the number of items changed in the backing database.
@@ -86,32 +116,10 @@ impl OverlayDB {
 	/// }
 	/// ```
 	pub fn commit(&mut self) -> Result<u32, UtilError> {
-		let mut ret = 0u32;
-		let mut deletes = 0usize;
-		for i in self.overlay.drain().into_iter() {
-			let (key, (value, rc)) = i;
-			if rc != 0 {
-				match self.payload(&key) {
-					Some(x) => {
-						let (back_value, back_rc) = x;
-						let total_rc: i32 = back_rc as i32 + rc;
-						if total_rc < 0 {
-							return Err(From::from(BaseDataError::NegativelyReferencedHash));
-						}
-						deletes += if self.put_payload(&key, (back_value, total_rc as u32)) {1} else {0};
-					}
-					None => {
-						if rc < 0 {
-							return Err(From::from(BaseDataError::NegativelyReferencedHash));
-						}
-						self.put_payload(&key, (value, rc as u32));
-					}
-				};
-				ret += 1;
-			}
-		}
-		trace!("OverlayDB::commit() deleted {} nodes", deletes);
-		Ok(ret)
+		let batch = DBTransaction::new();
+		let r = try!(self.commit_to_batch(&batch));
+		try!(self.backing.write(batch));
+		Ok(r)
 	}
 
 	/// Revert all operations on this object (i.e. `insert()`s and `kill()`s) since the
@@ -148,15 +156,15 @@ impl OverlayDB {
 	}
 
 	/// Put the refs and value of the given key, possibly deleting it from the db.
-	fn put_payload(&self, key: &H256, payload: (Bytes, u32)) -> bool {
+	fn put_payload(&self, batch: &DBTransaction, key: &H256, payload: (Bytes, u32)) -> bool {
 		if payload.1 > 0 {
 			let mut s = RlpStream::new_list(2);
 			s.append(&payload.1);
 			s.append(&payload.0);
-			self.backing.put(&key.bytes(), s.as_raw()).expect("Low-level database error. Some issue with your hard disk?");
+			batch.put(&key.bytes(), s.as_raw()).expect("Low-level database error. Some issue with your hard disk?");
 			false
 		} else {
-			self.backing.delete(&key.bytes()).expect("Low-level database error. Some issue with your hard disk?");
+			batch.delete(&key.bytes()).expect("Low-level database error. Some issue with your hard disk?");
 			true
 		}
 	}