diff --git a/ethcore/src/client/client.rs b/ethcore/src/client/client.rs
index 348911424ae..ff09f7c72a5 100644
--- a/ethcore/src/client/client.rs
+++ b/ethcore/src/client/client.rs
@@ -481,7 +481,7 @@ impl Importer {
 
 		let mut batch = DBTransaction::new();
 
-		let ancestry_actions = self.engine.ancestry_actions(&block, &mut chain.ancestry_with_metadata_iter(*parent));
+		let ancestry_actions = self.engine.ancestry_actions(&header, &mut chain.ancestry_with_metadata_iter(*parent));
 
 		let receipts = block.receipts;
 		let traces = block.traces.drain();
diff --git a/ethcore/src/engines/authority_round/mod.rs b/ethcore/src/engines/authority_round/mod.rs
index c6195d0b24c..1a54ccec1b6 100644
--- a/ethcore/src/engines/authority_round/mod.rs
+++ b/ethcore/src/engines/authority_round/mod.rs
@@ -798,6 +798,7 @@ impl AuthorityRound {
 				}
 			};
 
+			let epoch_transition_hash = epoch_manager.epoch_transition_hash;
 			let ancestry_iter = ancestry.map(|header| {
 				let mut signers = vec![*header.author()];
 				signers.extend(parent_empty_steps_signers.drain(..));
@@ -815,10 +816,11 @@ impl AuthorityRound {
 					None
 				}
 			})
-				.while_some();
+				.while_some()
+				.take_while(|&(h, _)| h != epoch_transition_hash);
 
-			if let Err(_) = epoch_manager.finality_checker.build_ancestry_subchain(ancestry_iter) {
-				debug!(target: "engine", "inconsistent validator set within epoch");
+			if let Err(e) = epoch_manager.finality_checker.build_ancestry_subchain(ancestry_iter) {
+				debug!(target: "engine", "inconsistent validator set within epoch: {:?}", e);
 				return Vec::new();
 			}
 		}
@@ -1448,9 +1450,9 @@ impl Engine<EthereumMachine> for AuthorityRound {
 		super::total_difficulty_fork_choice(new, current)
 	}
 
-	fn ancestry_actions(&self, block: &ExecutedBlock, ancestry: &mut Iterator<Item=ExtendedHeader>) -> Vec<AncestryAction> {
+	fn ancestry_actions(&self, header: &Header, ancestry: &mut Iterator<Item=ExtendedHeader>) -> Vec<AncestryAction> {
 		let finalized = self.build_finality(
-			block.header(),
+			header,
 			&mut ancestry.take_while(|e| !e.is_finalized).map(|e| e.header),
 		);
 
diff --git a/ethcore/src/engines/mod.rs b/ethcore/src/engines/mod.rs
index 9bf7fa92b3a..39f3ac20471 100644
--- a/ethcore/src/engines/mod.rs
+++ b/ethcore/src/engines/mod.rs
@@ -429,7 +429,7 @@ pub trait Engine<M: Machine>: Sync + Send {
 
 	/// Gather all ancestry actions. Called at the last stage when a block is committed. The Engine must guarantee that
 	/// the ancestry exists.
-	fn ancestry_actions(&self, _block: &M::LiveBlock, _ancestry: &mut Iterator<Item=M::ExtendedHeader>) -> Vec<AncestryAction> {
+	fn ancestry_actions(&self, _header: &M::Header, _ancestry: &mut Iterator<Item=M::ExtendedHeader>) -> Vec<AncestryAction> {
 		Vec::new()
 	}