diff --git a/ethcore/src/block.rs b/ethcore/src/block.rs
index d2cb128c4..7eb81f423 100644
--- a/ethcore/src/block.rs
+++ b/ethcore/src/block.rs
@@ -22,13 +22,13 @@
 //! and can be appended to with transactions and uncles.
 //!
 //! When ready, `OpenBlock` can be closed and turned into a `ClosedBlock`. A `ClosedBlock` can
-//! be reopend again by a miner under certain circumstances. On block close, state commit is
+//! be re-opend again by a miner under certain circumstances. On block close, state commit is
 //! performed.
 //!
 //! `LockedBlock` is a version of a `ClosedBlock` that cannot be reopened. It can be sealed
 //! using an engine.
 //!
-//! `ExecutedBlock` is an underlaying data structure used by all structs above to store block
+//! `ExecutedBlock` is an underlying data structure used by all structs above to store block
 //! related info.
 
 use std::{cmp, ops};
@@ -52,7 +52,7 @@ use vm::{EnvInfo, LastHashes};
 use hash::keccak;
 use rlp::{RlpStream, Encodable, encode_list};
 use types::transaction::{SignedTransaction, Error as TransactionError};
-use types::header::{Header, ExtendedHeader};
+use types::header::Header;
 use types::receipt::{Receipt, TransactionOutcome};
 
 /// Block that is ready for transactions to be added.
@@ -62,6 +62,7 @@ use types::receipt::{Receipt, TransactionOutcome};
 pub struct OpenBlock<'x> {
 	block: ExecutedBlock,
 	engine: &'x dyn Engine,
+	parent: Header,
 }
 
 /// Just like `OpenBlock`, except that we've applied `Engine::on_close_block`, finished up the non-seal header fields,
@@ -72,6 +73,7 @@ pub struct OpenBlock<'x> {
 pub struct ClosedBlock {
 	block: ExecutedBlock,
 	unclosed_state: State<StateDB>,
+	parent: Header,
 }
 
 /// Just like `ClosedBlock` except that we can't reopen it and it's faster.
@@ -102,7 +104,7 @@ pub struct ExecutedBlock {
 	pub receipts: Vec<Receipt>,
 	/// Hashes of already executed transactions.
 	pub transactions_set: HashSet<H256>,
-	/// Underlaying state.
+	/// Underlying state.
 	pub state: State<StateDB>,
 	/// Transaction traces.
 	pub traces: Tracing,
@@ -119,13 +121,13 @@ impl ExecutedBlock {
 			uncles: Default::default(),
 			receipts: Default::default(),
 			transactions_set: Default::default(),
-			state: state,
+			state,
 			traces: if tracing {
 				Tracing::enabled()
 			} else {
 				Tracing::Disabled
 			},
-			last_hashes: last_hashes,
+			last_hashes,
 		}
 	}
 
@@ -162,7 +164,7 @@ pub trait Drain {
 
 impl<'x> OpenBlock<'x> {
 	/// Create a new `OpenBlock` ready for transaction pushing.
-	pub fn new<'a, I: IntoIterator<Item = ExtendedHeader>>(
+	pub fn new<'a>(
 		engine: &'x dyn Engine,
 		factories: Factories,
 		tracing: bool,
@@ -173,14 +175,11 @@ impl<'x> OpenBlock<'x> {
 		gas_range_target: (U256, U256),
 		extra_data: Bytes,
 		is_epoch_begin: bool,
-		ancestry: I,
 	) -> Result<Self, Error> {
 		let number = parent.number() + 1;
 		let state = State::from_existing(db, parent.state_root().clone(), engine.account_start_nonce(number), factories)?;
-		let mut r = OpenBlock {
-			block: ExecutedBlock::new(state, last_hashes, tracing),
-			engine: engine,
-		};
+
+		let mut r = OpenBlock { block: ExecutedBlock::new(state, last_hashes, tracing), engine, parent: parent.clone() };
 
 		r.block.header.set_parent_hash(parent.hash());
 		r.block.header.set_number(number);
@@ -195,7 +194,7 @@ impl<'x> OpenBlock<'x> {
 		engine.populate_from_parent(&mut r.block.header, parent);
 
 		engine.machine().on_new_block(&mut r.block)?;
-		engine.on_new_block(&mut r.block, is_epoch_begin, &mut ancestry.into_iter())?;
+		engine.on_new_block(&mut r.block, is_epoch_begin)?;
 
 		Ok(r)
 	}
@@ -297,19 +296,20 @@ impl<'x> OpenBlock<'x> {
 	/// Turn this into a `ClosedBlock`.
 	pub fn close(self) -> Result<ClosedBlock, Error> {
 		let unclosed_state = self.block.state.clone();
+		let parent = self.parent.clone();
 		let locked = self.close_and_lock()?;
 
 		Ok(ClosedBlock {
 			block: locked.block,
 			unclosed_state,
+			parent,
 		})
 	}
 
 	/// Turn this into a `LockedBlock`.
 	pub fn close_and_lock(self) -> Result<LockedBlock, Error> {
 		let mut s = self;
-
-		s.engine.on_close_block(&mut s.block)?;
+		s.engine.on_close_block(&mut s.block, &s.parent)?;
 		s.block.state.commit()?;
 
 		s.block.header.set_transactions_root(ordered_trie_root(s.block.transactions.iter().map(|e| e.rlp_bytes())));
@@ -378,10 +378,8 @@ impl ClosedBlock {
 		// revert rewards (i.e. set state back at last transaction's state).
 		let mut block = self.block;
 		block.state = self.unclosed_state;
-		OpenBlock {
-			block: block,
-			engine: engine,
-		}
+		let parent = self.parent;
+		OpenBlock { block, engine, parent }
 	}
 }
 
@@ -479,7 +477,6 @@ pub(crate) fn enact(
 	last_hashes: Arc<LastHashes>,
 	factories: Factories,
 	is_epoch_begin: bool,
-	ancestry: &mut dyn Iterator<Item=ExtendedHeader>,
 ) -> Result<LockedBlock, Error> {
 	// For trace log
 	let trace_state = if log_enabled!(target: "enact", ::log::Level::Trace) {
@@ -501,7 +498,6 @@ pub(crate) fn enact(
 		(3141562.into(), 31415620.into()),
 		vec![],
 		is_epoch_begin,
-		ancestry,
 	)?;
 
 	if let Some(ref s) = trace_state {
@@ -522,7 +518,7 @@ pub(crate) fn enact(
 	b.close_and_lock()
 }
 
-/// Enact the block given by `block_bytes` using `engine` on the database `db` with given `parent` block header
+/// Enact the block given by `block_bytes` using `engine` on the database `db` with the given `parent` block header
 pub fn enact_verified(
 	block: PreverifiedBlock,
 	engine: &dyn Engine,
@@ -532,7 +528,6 @@ pub fn enact_verified(
 	last_hashes: Arc<LastHashes>,
 	factories: Factories,
 	is_epoch_begin: bool,
-	ancestry: &mut dyn Iterator<Item=ExtendedHeader>,
 ) -> Result<LockedBlock, Error> {
 
 	enact(
@@ -546,7 +541,6 @@ pub fn enact_verified(
 		last_hashes,
 		factories,
 		is_epoch_begin,
-		ancestry,
 	)
 }
 
@@ -608,7 +602,6 @@ mod tests {
 			(3141562.into(), 31415620.into()),
 			vec![],
 			false,
-			None,
 		)?;
 
 		b.populate_from(&header);
@@ -643,7 +636,7 @@ mod tests {
 		let genesis_header = spec.genesis_header();
 		let db = spec.ensure_db_good(get_temp_state_db(), &Default::default()).unwrap();
 		let last_hashes = Arc::new(vec![genesis_header.hash()]);
-		let b = OpenBlock::new(&*spec.engine, Default::default(), false, db, &genesis_header, last_hashes, Address::zero(), (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b = OpenBlock::new(&*spec.engine, Default::default(), false, db, &genesis_header, last_hashes, Address::zero(), (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b = b.close_and_lock().unwrap();
 		let _ = b.seal(&*spec.engine, vec![]);
 	}
@@ -657,7 +650,7 @@ mod tests {
 
 		let db = spec.ensure_db_good(get_temp_state_db(), &Default::default()).unwrap();
 		let last_hashes = Arc::new(vec![genesis_header.hash()]);
-		let b = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes.clone(), Address::zero(), (3141562.into(), 31415620.into()), vec![], false, None).unwrap()
+		let b = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes.clone(), Address::zero(), (3141562.into(), 31415620.into()), vec![], false).unwrap()
 			.close_and_lock().unwrap().seal(engine, vec![]).unwrap();
 		let orig_bytes = b.rlp_bytes();
 		let orig_db = b.drain().state.drop().1;
@@ -682,7 +675,7 @@ mod tests {
 
 		let db = spec.ensure_db_good(get_temp_state_db(), &Default::default()).unwrap();
 		let last_hashes = Arc::new(vec![genesis_header.hash()]);
-		let mut open_block = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes.clone(), Address::zero(), (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let mut open_block = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes.clone(), Address::zero(), (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let mut uncle1_header = Header::new();
 		uncle1_header.set_extra_data(b"uncle1".to_vec());
 		let mut uncle2_header = Header::new();
diff --git a/ethcore/src/client/client.rs b/ethcore/src/client/client.rs
index 7678314f0..e9847437c 100644
--- a/ethcore/src/client/client.rs
+++ b/ethcore/src/client/client.rs
@@ -407,7 +407,6 @@ impl Importer {
 			last_hashes,
 			client.factories.clone(),
 			is_epoch_begin,
-			&mut chain.ancestry_with_metadata_iter(*header.parent_hash()),
 		);
 
 		let mut locked_block = match enact_result {
@@ -2361,7 +2360,6 @@ impl PrepareOpenBlock for Client {
 			gas_range_target,
 			extra_data,
 			is_epoch_begin,
-			chain.ancestry_with_metadata_iter(best_header.hash()),
 		)?;
 
 		// Add uncles
diff --git a/ethcore/src/client/test_client.rs b/ethcore/src/client/test_client.rs
index 9eb1b14eb..7894a665d 100644
--- a/ethcore/src/client/test_client.rs
+++ b/ethcore/src/client/test_client.rs
@@ -417,7 +417,6 @@ impl PrepareOpenBlock for TestBlockChainClient {
 			gas_range_target,
 			extra_data,
 			false,
-			None,
 		)?;
 		// TODO [todr] Override timestamp for predictability
 		open_block.set_timestamp(*self.latest_block_timestamp.read());
diff --git a/ethcore/src/engines/authority_round/mod.rs b/ethcore/src/engines/authority_round/mod.rs
index 97305efad..cb9b8a499 100644
--- a/ethcore/src/engines/authority_round/mod.rs
+++ b/ethcore/src/engines/authority_round/mod.rs
@@ -1211,7 +1211,6 @@ impl Engine for AuthorityRound {
 		&self,
 		block: &mut ExecutedBlock,
 		epoch_begin: bool,
-		_ancestry: &mut dyn Iterator<Item=ExtendedHeader>,
 	) -> Result<(), Error> {
 		// with immediate transitions, we don't use the epoch mechanism anyway.
 		// the genesis is always considered an epoch, but we ignore it intentionally.
@@ -1236,26 +1235,18 @@ impl Engine for AuthorityRound {
 	}
 
 	/// Apply the block reward on finalisation of the block.
-	fn on_close_block(&self, block: &mut ExecutedBlock) -> Result<(), Error> {
+	fn on_close_block(
+		&self,
+		block: &mut ExecutedBlock,
+		parent: &Header,
+	) -> Result<(), Error> {
 		let mut beneficiaries = Vec::new();
 		if block.header.number() >= self.empty_steps_transition {
 			let empty_steps = if block.header.seal().is_empty() {
 				// this is a new block, calculate rewards based on the empty steps messages we have accumulated
-				let client = match self.client.read().as_ref().and_then(|weak| weak.upgrade()) {
-					Some(client) => client,
-					None => {
-						debug!(target: "engine", "Unable to close block: missing client ref.");
-						return Err(EngineError::RequiresClient.into())
-					},
-				};
-
-				let parent = client.block_header(::client::BlockId::Hash(*block.header.parent_hash()))
-					.expect("hash is from parent; parent header must exist; qed")
-					.decode()?;
-
-				let parent_step = header_step(&parent, self.empty_steps_transition)?;
+				let parent_step = header_step(parent, self.empty_steps_transition)?;
 				let current_step = self.step.inner.load();
-				self.empty_steps(parent_step.into(), current_step.into(), parent.hash())
+				self.empty_steps(parent_step, current_step, parent.hash())
 			} else {
 				// we're verifying a block, extract empty steps from the seal
 				header_empty_steps(&block.header)?
@@ -1707,9 +1698,9 @@ mod tests {
 		let db1 = spec.ensure_db_good(get_temp_state_db(), &Default::default()).unwrap();
 		let db2 = spec.ensure_db_good(get_temp_state_db(), &Default::default()).unwrap();
 		let last_hashes = Arc::new(vec![genesis_header.hash()]);
-		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b1 = b1.close_and_lock().unwrap();
-		let b2 = OpenBlock::new(engine, Default::default(), false, db2, &genesis_header, last_hashes, addr2, (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b2 = OpenBlock::new(engine, Default::default(), false, db2, &genesis_header, last_hashes, addr2, (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b2 = b2.close_and_lock().unwrap();
 
 		engine.set_signer(Box::new((tap.clone(), addr1, "1".into())));
@@ -1741,9 +1732,9 @@ mod tests {
 		let db2 = spec.ensure_db_good(get_temp_state_db(), &Default::default()).unwrap();
 		let last_hashes = Arc::new(vec![genesis_header.hash()]);
 
-		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b1 = b1.close_and_lock().unwrap();
-		let b2 = OpenBlock::new(engine, Default::default(), false, db2, &genesis_header, last_hashes, addr2, (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b2 = OpenBlock::new(engine, Default::default(), false, db2, &genesis_header, last_hashes, addr2, (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b2 = b2.close_and_lock().unwrap();
 
 		engine.set_signer(Box::new((tap.clone(), addr1, "1".into())));
@@ -1991,7 +1982,7 @@ mod tests {
 
 		engine.set_signer(Box::new((tap.clone(), addr1, "1".into())));
 
-		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b1 = b1.close_and_lock().unwrap();
 
 		// the block is empty so we don't seal and instead broadcast an empty step message
@@ -2029,7 +2020,7 @@ mod tests {
 		engine.register_client(Arc::downgrade(&client) as _);
 
 		// step 2
-		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b1 = b1.close_and_lock().unwrap();
 
 		// since the block is empty it isn't sealed and we generate empty steps
@@ -2038,7 +2029,7 @@ mod tests {
 		engine.step();
 
 		// step 3
-		let mut b2 = OpenBlock::new(engine, Default::default(), false, db2, &genesis_header, last_hashes.clone(), addr2, (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let mut b2 = OpenBlock::new(engine, Default::default(), false, db2, &genesis_header, last_hashes.clone(), addr2, (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		b2.push_transaction(Transaction {
 			action: Action::Create,
 			nonce: U256::from(0),
@@ -2082,7 +2073,7 @@ mod tests {
 		engine.register_client(Arc::downgrade(&client) as _);
 
 		// step 2
-		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b1 = b1.close_and_lock().unwrap();
 
 		// since the block is empty it isn't sealed and we generate empty steps
@@ -2091,7 +2082,7 @@ mod tests {
 		engine.step();
 
 		// step 3
-		let b2 = OpenBlock::new(engine, Default::default(), false, db2, &genesis_header, last_hashes.clone(), addr2, (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b2 = OpenBlock::new(engine, Default::default(), false, db2, &genesis_header, last_hashes.clone(), addr2, (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b2 = b2.close_and_lock().unwrap();
 		engine.set_signer(Box::new((tap.clone(), addr2, "0".into())));
 		assert_eq!(engine.generate_seal(&b2, &genesis_header), Seal::None);
@@ -2099,7 +2090,7 @@ mod tests {
 
 		// step 4
 		// the spec sets the maximum_empty_steps to 2 so we will now seal an empty block and include the empty step messages
-		let b3 = OpenBlock::new(engine, Default::default(), false, db3, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b3 = OpenBlock::new(engine, Default::default(), false, db3, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b3 = b3.close_and_lock().unwrap();
 
 		engine.set_signer(Box::new((tap.clone(), addr1, "1".into())));
@@ -2132,7 +2123,7 @@ mod tests {
 		engine.register_client(Arc::downgrade(&client) as _);
 
 		// step 2
-		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b1 = b1.close_and_lock().unwrap();
 
 		// since the block is empty it isn't sealed and we generate empty steps
@@ -2142,7 +2133,7 @@ mod tests {
 
 		// step 3
 		// the signer of the accumulated empty step message should be rewarded
-		let b2 = OpenBlock::new(engine, Default::default(), false, db2, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b2 = OpenBlock::new(engine, Default::default(), false, db2, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let addr1_balance = b2.state.balance(&addr1).unwrap();
 
 		// after closing the block `addr1` should be reward twice, one for the included empty step message and another for block creation
@@ -2242,7 +2233,6 @@ mod tests {
 			(3141562.into(), 31415620.into()),
 			vec![],
 			false,
-			None,
 		).unwrap();
 		let b1 = b1.close_and_lock().unwrap();
 
@@ -2264,7 +2254,6 @@ mod tests {
 			(3141562.into(), 31415620.into()),
 			vec![],
 			false,
-			None,
 		).unwrap();
 		let addr1_balance = b2.state.balance(&addr1).unwrap();
 
diff --git a/ethcore/src/engines/basic_authority.rs b/ethcore/src/engines/basic_authority.rs
index 18afc51ce..b08512b79 100644
--- a/ethcore/src/engines/basic_authority.rs
+++ b/ethcore/src/engines/basic_authority.rs
@@ -268,7 +268,7 @@ mod tests {
 		let genesis_header = spec.genesis_header();
 		let db = spec.ensure_db_good(get_temp_state_db(), &Default::default()).unwrap();
 		let last_hashes = Arc::new(vec![genesis_header.hash()]);
-		let b = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes, addr, (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes, addr, (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b = b.close_and_lock().unwrap();
 		if let Seal::Regular(seal) = engine.generate_seal(&b, &genesis_header) {
 			assert!(b.try_seal(engine, seal).is_ok());
diff --git a/ethcore/src/engines/clique/mod.rs b/ethcore/src/engines/clique/mod.rs
index 9c8e1823f..89bcef94c 100644
--- a/ethcore/src/engines/clique/mod.rs
+++ b/ethcore/src/engines/clique/mod.rs
@@ -368,13 +368,16 @@ impl Engine for Clique {
 		&self,
 		_block: &mut ExecutedBlock,
 		_epoch_begin: bool,
-		_ancestry: &mut dyn Iterator<Item=ExtendedHeader>,
 	) -> Result<(), Error> {
 		Ok(())
 	}
 
 	// Clique has no block reward.
-	fn on_close_block(&self, _block: &mut ExecutedBlock) -> Result<(), Error> {
+	fn on_close_block(
+		&self,
+		_block: &mut ExecutedBlock,
+		_parent_header: &Header
+	) -> Result<(), Error> {
 		Ok(())
 	}
 
diff --git a/ethcore/src/engines/clique/tests.rs b/ethcore/src/engines/clique/tests.rs
index 76140284f..97e218a05 100644
--- a/ethcore/src/engines/clique/tests.rs
+++ b/ethcore/src/engines/clique/tests.rs
@@ -111,7 +111,7 @@ impl CliqueTester {
 
 	/// Get signers after a certain state
 	// This is generally used to fetch the state after a test has been executed and checked against
-	// the intial list of signers provided in the test
+	// the initial list of signers provided in the test
 	pub fn clique_signers(&self, hash: &H256) -> impl Iterator<Item = Address> {
 		self.get_state_at_block(hash).signers().clone().into_iter()
 	}
@@ -171,7 +171,6 @@ impl CliqueTester {
 			(3141562.into(), 31415620.into()),
 			extra_data,
 			false,
-			None,
 		).unwrap();
 
 		{
diff --git a/ethcore/src/engines/instant_seal.rs b/ethcore/src/engines/instant_seal.rs
index 27f133424..58fbfeed1 100644
--- a/ethcore/src/engines/instant_seal.rs
+++ b/ethcore/src/engines/instant_seal.rs
@@ -110,7 +110,7 @@ mod tests {
 		let db = spec.ensure_db_good(get_temp_state_db(), &Default::default()).unwrap();
 		let genesis_header = spec.genesis_header();
 		let last_hashes = Arc::new(vec![genesis_header.hash()]);
-		let b = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes, Address::zero(), (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes, Address::zero(), (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b = b.close_and_lock().unwrap();
 		if let Seal::Regular(seal) = engine.generate_seal(&b, &genesis_header) {
 			assert!(b.try_seal(engine, seal).is_ok());
diff --git a/ethcore/src/engines/mod.rs b/ethcore/src/engines/mod.rs
index c550f74c2..b0207b075 100644
--- a/ethcore/src/engines/mod.rs
+++ b/ethcore/src/engines/mod.rs
@@ -304,13 +304,16 @@ pub trait Engine: Sync + Send {
 		&self,
 		_block: &mut ExecutedBlock,
 		_epoch_begin: bool,
-		_ancestry: &mut dyn Iterator<Item = ExtendedHeader>,
 	) -> Result<(), Error> {
 		Ok(())
 	}
 
 	/// Block transformation functions, after the transactions.
-	fn on_close_block(&self, _block: &mut ExecutedBlock) -> Result<(), Error> {
+	fn on_close_block(
+		&self,
+		_block: &mut ExecutedBlock,
+		_parent_header: &Header,
+	) -> Result<(), Error> {
 		Ok(())
 	}
 
diff --git a/ethcore/src/engines/null_engine.rs b/ethcore/src/engines/null_engine.rs
index a29196977..71cb9d459 100644
--- a/ethcore/src/engines/null_engine.rs
+++ b/ethcore/src/engines/null_engine.rs
@@ -61,7 +61,11 @@ impl Engine for NullEngine {
 
 	fn machine(&self) -> &Machine { &self.machine }
 
-	fn on_close_block(&self, block: &mut ExecutedBlock) -> Result<(), Error> {
+	fn on_close_block(
+		&self,
+		block: &mut ExecutedBlock,
+		_parent_header: &Header
+	) -> Result<(), Error> {
 		use std::ops::Shr;
 
 		let author = *block.header.author();
diff --git a/ethcore/src/ethereum/ethash.rs b/ethcore/src/ethereum/ethash.rs
index c29f960e5..a6540ab79 100644
--- a/ethcore/src/ethereum/ethash.rs
+++ b/ethcore/src/ethereum/ethash.rs
@@ -239,7 +239,7 @@ impl Engine for Arc<Ethash> {
 
 	/// Apply the block reward on finalisation of the block.
 	/// This assumes that all uncles are valid uncles (i.e. of at least one generation before the current).
-	fn on_close_block(&self, block: &mut ExecutedBlock) -> Result<(), Error> {
+	fn on_close_block(&self, block: &mut ExecutedBlock, _parent_header: &Header) -> Result<(), Error> {
 		use std::ops::Shr;
 
 		let author = *block.header.author();
@@ -540,7 +540,7 @@ mod tests {
 		let genesis_header = spec.genesis_header();
 		let db = spec.ensure_db_good(get_temp_state_db(), &Default::default()).unwrap();
 		let last_hashes = Arc::new(vec![genesis_header.hash()]);
-		let b = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes, Address::zero(), (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes, Address::zero(), (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b = b.close().unwrap();
 		assert_eq!(b.state.balance(&Address::zero()).unwrap(), U256::from_str("4563918244f40000").unwrap());
 	}
@@ -589,7 +589,7 @@ mod tests {
 		let genesis_header = spec.genesis_header();
 		let db = spec.ensure_db_good(get_temp_state_db(), &Default::default()).unwrap();
 		let last_hashes = Arc::new(vec![genesis_header.hash()]);
-		let mut b = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes, Address::zero(), (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let mut b = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes, Address::zero(), (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let mut uncle = Header::new();
 		let uncle_author = Address::from_str("ef2d6d194084c2de36e0dabfce45d046b37d1106").unwrap();
 		uncle.set_author(uncle_author);
@@ -607,7 +607,7 @@ mod tests {
 		let genesis_header = spec.genesis_header();
 		let db = spec.ensure_db_good(get_temp_state_db(), &Default::default()).unwrap();
 		let last_hashes = Arc::new(vec![genesis_header.hash()]);
-		let b = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes, Address::zero(), (3141562.into(), 31415620.into()), vec![], false, None).unwrap();
+		let b = OpenBlock::new(engine, Default::default(), false, db, &genesis_header, last_hashes, Address::zero(), (3141562.into(), 31415620.into()), vec![], false).unwrap();
 		let b = b.close().unwrap();
 
 		let ubi_contract = Address::from_str("00efdd5883ec628983e9063c7d969fe268bbf310").unwrap();
diff --git a/ethcore/src/miner/miner.rs b/ethcore/src/miner/miner.rs
index c35423d74..e933d7d58 100644
--- a/ethcore/src/miner/miner.rs
+++ b/ethcore/src/miner/miner.rs
@@ -548,7 +548,7 @@ impl Miner {
 					}
 				},
 				// Invalid nonce error can happen only if previous transaction is skipped because of gas limit.
-				// If there is errornous state of transaction queue it will be fixed when next block is imported.
+				// If there is erroneous state of transaction queue it will be fixed when next block is imported.
 				Err(Error::Execution(ExecutionError::InvalidNonce { expected, got })) => {
 					debug!(target: "miner", "Skipping adding transaction to block because of invalid nonce: {:?} (expected: {:?}, got: {:?})", hash, expected, got);
 				},
diff --git a/ethcore/src/test_helpers.rs b/ethcore/src/test_helpers.rs
index 6bdaeadf9..5137aade0 100644
--- a/ethcore/src/test_helpers.rs
+++ b/ethcore/src/test_helpers.rs
@@ -155,7 +155,6 @@ pub fn generate_dummy_client_with_spec_and_data<F>(test_spec: F, block_number: u
 			(3141562.into(), 31415620.into()),
 			vec![],
 			false,
-			None,
 		).unwrap();
 		rolling_timestamp += 10;
 		b.set_timestamp(rolling_timestamp);
diff --git a/ethcore/src/tests/client.rs b/ethcore/src/tests/client.rs
index 093c55a91..343751b04 100644
--- a/ethcore/src/tests/client.rs
+++ b/ethcore/src/tests/client.rs
@@ -117,7 +117,7 @@ fn query_none_block() {
 		Arc::new(Miner::new_for_tests(&spec, None)),
 		IoChannel::disconnected(),
 	).unwrap();
-    let non_existant = client.block_header(BlockId::Number(188));
+	let non_existant = client.block_header(BlockId::Number(188));
 	assert!(non_existant.is_none());
 }
 
diff --git a/ethcore/src/tests/trace.rs b/ethcore/src/tests/trace.rs
index 882fed443..b80c74851 100644
--- a/ethcore/src/tests/trace.rs
+++ b/ethcore/src/tests/trace.rs
@@ -87,7 +87,6 @@ fn can_trace_block_and_uncle_reward() {
 		(3141562.into(), 31415620.into()),
 		vec![],
 		false,
-		None,
 	).unwrap();
 	rolling_timestamp += 10;
 	root_block.set_timestamp(rolling_timestamp);
@@ -116,7 +115,6 @@ fn can_trace_block_and_uncle_reward() {
 		(3141562.into(), 31415620.into()),
 		vec![],
 		false,
-		None,
 	).unwrap();
 	rolling_timestamp += 10;
 	parent_block.set_timestamp(rolling_timestamp);
@@ -144,7 +142,6 @@ fn can_trace_block_and_uncle_reward() {
 		(3141562.into(), 31415620.into()),
 		vec![],
 		false,
-		None,
 		).unwrap();
 	rolling_timestamp += 10;
 	block.set_timestamp(rolling_timestamp);