diff --git a/ethcore/src/blockchain.rs b/ethcore/src/blockchain.rs
index e75676855..9240ff800 100644
--- a/ethcore/src/blockchain.rs
+++ b/ethcore/src/blockchain.rs
@@ -859,7 +859,7 @@ mod tests {
 		let transactions = bc.transactions(&b1_hash).unwrap();
 		assert_eq!(transactions.len(), 7);
 		for t in transactions {
-			assert_eq!(bc.transaction(&t.hash()).unwrap(), t);
+			assert_eq!(bc.transaction(&bc.transaction_address(&t.hash()).unwrap()).unwrap(), t);
 		}
 	}
 }
diff --git a/ethcore/src/tests/client.rs b/ethcore/src/tests/client.rs
index 697647187..8132b26cf 100644
--- a/ethcore/src/tests/client.rs
+++ b/ethcore/src/tests/client.rs
@@ -14,7 +14,7 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
-use client::{BlockChainClient,Client};
+use client::{BlockChainClient, Client, BlockId};
 use tests::helpers::*;
 use common::*;
 
@@ -44,7 +44,7 @@ fn imports_good_block() {
 	client.flush_queue();
 	client.import_verified_blocks(&IoChannel::disconnected());
 
-	let block = client.block_header_at(1).unwrap();
+	let block = client.block_header(BlockId::Number(1)).unwrap();
 	assert!(!block.is_empty());
 }
 
@@ -53,7 +53,7 @@ fn query_none_block() {
 	let dir = RandomTempPath::new();
 	let client = Client::new(get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
 
-    let non_existant = client.block_header_at(188);
+    let non_existant = client.block_header(BlockId::Number(188));
 	assert!(non_existant.is_none());
 }
 
@@ -61,7 +61,7 @@ fn query_none_block() {
 fn query_bad_block() {
 	let client_result = get_test_client_with_blocks(vec![get_bad_state_dummy_block()]);
 	let client = client_result.reference();
-	let bad_block:Option<Bytes> = client.block_header_at(1);
+	let bad_block:Option<Bytes> = client.block_header(BlockId::Number(1));
 
 	assert!(bad_block.is_none());
 }
@@ -80,7 +80,7 @@ fn returns_chain_info() {
 fn imports_block_sequence() {
 	let client_result = generate_dummy_client(6);
 	let client = client_result.reference();
-	let block = client.block_header_at(5).unwrap();
+	let block = client.block_header(BlockId::Number(5)).unwrap();
 
 	assert!(!block.is_empty());
 }
diff --git a/sync/src/chain.rs b/sync/src/chain.rs
index b3dfc71f5..91e1ccbd5 100644
--- a/sync/src/chain.rs
+++ b/sync/src/chain.rs
@@ -1061,6 +1061,7 @@ impl ChainSync {
 						for block_hash in route.blocks {
 							let mut hash_rlp = RlpStream::new_list(2);
 							let difficulty = chain.block_total_difficulty(BlockId::Hash(block_hash.clone())).expect("Mallformed block without a difficulty on the chain!");
+		
 							hash_rlp.append(&block_hash);
 							hash_rlp.append(&difficulty);
 							rlp_stream.append_raw(&hash_rlp.out(), 1);
diff --git a/sync/src/tests/chain.rs b/sync/src/tests/chain.rs
index 6526d8500..f560f4ca6 100644
--- a/sync/src/tests/chain.rs
+++ b/sync/src/tests/chain.rs
@@ -15,7 +15,7 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 use util::*;
-use ethcore::client::{BlockChainClient};
+use ethcore::client::{BlockChainClient, BlockId};
 use io::SyncIo;
 use chain::{SyncState};
 use super::helpers::*;
@@ -27,7 +27,7 @@ fn two_peers() {
 	net.peer_mut(1).chain.add_blocks(1000, false);
 	net.peer_mut(2).chain.add_blocks(1000, false);
 	net.sync();
-	assert!(net.peer(0).chain.block_at(1000).is_some());
+	assert!(net.peer(0).chain.block(BlockId::Number(1000)).is_some());
 	assert_eq!(net.peer(0).chain.blocks.read().unwrap().deref(), net.peer(1).chain.blocks.read().unwrap().deref());
 }
 
@@ -60,7 +60,7 @@ fn empty_blocks() {
 		net.peer_mut(2).chain.add_blocks(5, n % 2 == 0);
 	}
 	net.sync();
-	assert!(net.peer(0).chain.block_at(1000).is_some());
+	assert!(net.peer(0).chain.block(BlockId::Number(1000)).is_some());
 	assert_eq!(net.peer(0).chain.blocks.read().unwrap().deref(), net.peer(1).chain.blocks.read().unwrap().deref());
 }
 
@@ -148,4 +148,4 @@ fn propagade_blocks() {
 	assert!(!net.peer(0).queue.is_empty());
 	// NEW_BLOCK_PACKET
 	assert_eq!(0x07, net.peer(0).queue[0].packet_id);
-}
\ No newline at end of file
+}
diff --git a/sync/src/tests/helpers.rs b/sync/src/tests/helpers.rs
index f8c08dc93..384b5bd65 100644
--- a/sync/src/tests/helpers.rs
+++ b/sync/src/tests/helpers.rs
@@ -15,7 +15,7 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 use util::*;
-use ethcore::client::{BlockChainClient, BlockStatus, TreeRoute, BlockChainInfo};
+use ethcore::client::{BlockChainClient, BlockStatus, TreeRoute, BlockChainInfo, TransactionId, BlockId};
 use ethcore::block_queue::BlockQueueInfo;
 use ethcore::header::{Header as BlockHeader, BlockNumber};
 use ethcore::error::*;
@@ -23,7 +23,6 @@ use io::SyncIo;
 use chain::{ChainSync};
 use ethcore::receipt::Receipt;
 use ethcore::transaction::LocalizedTransaction;
-use ethcore::blockchain::TransactionId;
 
 pub struct TestBlockChainClient {
 	pub blocks: RwLock<HashMap<H256, Bytes>>,
@@ -77,10 +76,17 @@ impl TestBlockChainClient {
 		let index = blocks_read.len() - delta;
 		blocks_read[&index].clone()
 	}
+
+	fn block_hash(&self, id: BlockId) -> Option<H256> {
+		match id {
+			BlockId::Hash(hash) => Some(hash),
+			BlockId::Number(n) => self.numbers.read().unwrap().get(&(n as usize)).cloned()
+		}
+	}
 }
 
 impl BlockChainClient for TestBlockChainClient {
-	fn block_total_difficulty(&self, _h: &H256) -> Option<U256> {
+	fn block_total_difficulty(&self, _id: BlockId) -> Option<U256> {
 		Some(U256::zero())
 	}
 
@@ -92,51 +98,28 @@ impl BlockChainClient for TestBlockChainClient {
 		unimplemented!();
 	}
 
-	fn block_header(&self, h: &H256) -> Option<Bytes> {
-		self.blocks.read().unwrap().get(h).map(|r| Rlp::new(r).at(0).as_raw().to_vec())
+	fn block_header(&self, id: BlockId) -> Option<Bytes> {
+		self.block_hash(id).and_then(|hash| self.blocks.read().unwrap().get(&hash).map(|r| Rlp::new(r).at(0).as_raw().to_vec()))
 	}
 
-	fn block_body(&self, h: &H256) -> Option<Bytes> {
-		self.blocks.read().unwrap().get(h).map(|r| {
+	fn block_body(&self, id: BlockId) -> Option<Bytes> {
+		self.block_hash(id).and_then(|hash| self.blocks.read().unwrap().get(&hash).map(|r| {
 			let mut stream = RlpStream::new_list(2);
 			stream.append_raw(Rlp::new(&r).at(1).as_raw(), 1);
 			stream.append_raw(Rlp::new(&r).at(2).as_raw(), 1);
 			stream.out()
-		})
+		}))
 	}
 
-	fn block(&self, h: &H256) -> Option<Bytes> {
-		self.blocks.read().unwrap().get(h).cloned()
+	fn block(&self, id: BlockId) -> Option<Bytes> {
+		self.block_hash(id).and_then(|hash| self.blocks.read().unwrap().get(&hash).cloned())
 	}
 
-	fn block_status(&self, h: &H256) -> BlockStatus {
-		match self.blocks.read().unwrap().get(h) {
-			Some(_) => BlockStatus::InChain,
-			None => BlockStatus::Unknown
-		}
-	}
-
-	fn block_total_difficulty_at(&self, _number: BlockNumber) -> Option<U256> {
-		unimplemented!();
-	}
-
-	fn block_header_at(&self, n: BlockNumber) -> Option<Bytes> {
-		self.numbers.read().unwrap().get(&(n as usize)).and_then(|h| self.block_header(h))
-	}
-
-	fn block_body_at(&self, n: BlockNumber) -> Option<Bytes> {
-		self.numbers.read().unwrap().get(&(n as usize)).and_then(|h| self.block_body(h))
-	}
-
-	fn block_at(&self, n: BlockNumber) -> Option<Bytes> {
-		self.numbers.read().unwrap().get(&(n as usize)).map(|h| self.blocks.read().unwrap().get(h).unwrap().clone())
-	}
-
-	fn block_status_at(&self, n: BlockNumber) -> BlockStatus {
-		if (n as usize) < self.blocks.read().unwrap().len() {
-			BlockStatus::InChain
-		} else {
-			BlockStatus::Unknown
+	fn block_status(&self, id: BlockId) -> BlockStatus {
+		match id {
+			BlockId::Number(number) if (number as usize) < self.blocks.read().unwrap().len() => BlockStatus::InChain,
+			BlockId::Hash(ref hash) if self.blocks.read().unwrap().get(hash).is_some() => BlockStatus::InChain,
+			_ => BlockStatus::Unknown
 		}
 	}