diff --git a/ethcore/src/block.rs b/ethcore/src/block.rs
index 7ec8ed4ce..db0bac614 100644
--- a/ethcore/src/block.rs
+++ b/ethcore/src/block.rs
@@ -17,7 +17,7 @@
 //! Blockchain block.
 
 use common::*;
-use engine::*;
+use engines::Engine;
 use state::*;
 use verification::PreverifiedBlock;
 use trace::FlatTrace;
diff --git a/ethcore/src/block_queue.rs b/ethcore/src/block_queue.rs
index bd8060996..6772c0461 100644
--- a/ethcore/src/block_queue.rs
+++ b/ethcore/src/block_queue.rs
@@ -22,7 +22,7 @@ use std::sync::{Condvar as SCondvar, Mutex as SMutex};
 use util::*;
 use verification::*;
 use error::*;
-use engine::Engine;
+use engines::Engine;
 use views::*;
 use header::*;
 use service::*;
diff --git a/ethcore/src/client/client.rs b/ethcore/src/client/client.rs
index 06ff5bd8c..eb06ef0ca 100644
--- a/ethcore/src/client/client.rs
+++ b/ethcore/src/client/client.rs
@@ -40,7 +40,7 @@ use header::BlockNumber;
 use state::State;
 use spec::Spec;
 use basic_types::Seal;
-use engine::Engine;
+use engines::Engine;
 use views::HeaderView;
 use service::ClientIoMessage;
 use env_info::LastHashes;
diff --git a/ethcore/src/basic_authority.rs b/ethcore/src/engines/basic_authority.rs
similarity index 97%
rename from ethcore/src/basic_authority.rs
rename to ethcore/src/engines/basic_authority.rs
index b5b199c82..525b825b9 100644
--- a/ethcore/src/basic_authority.rs
+++ b/ethcore/src/engines/basic_authority.rs
@@ -19,8 +19,8 @@
 use common::*;
 use account_provider::AccountProvider;
 use block::*;
-use spec::{CommonParams, Spec};
-use engine::*;
+use spec::CommonParams;
+use engines::Engine;
 use evm::Schedule;
 use ethjson;
 
@@ -176,16 +176,16 @@ impl Header {
 	}
 }
 
-/// Create a new test chain spec with `BasicAuthority` consensus engine.
-pub fn new_test_authority() -> Spec { Spec::load(include_bytes!("../res/test_authority.json")) }
-
 #[cfg(test)]
 mod tests {
-	use super::*;
 	use common::*;
 	use block::*;
 	use tests::helpers::*;
 	use account_provider::AccountProvider;
+	use spec::Spec;
+
+	/// Create a new test chain spec with `BasicAuthority` consensus engine.
+	fn new_test_authority() -> Spec { Spec::load(include_bytes!("../../res/test_authority.json")) }
 
 	#[test]
 	fn has_valid_metadata() {
diff --git a/ethcore/src/engine.rs b/ethcore/src/engines/mod.rs
similarity index 97%
rename from ethcore/src/engine.rs
rename to ethcore/src/engines/mod.rs
index e78f84c13..25feed74d 100644
--- a/ethcore/src/engine.rs
+++ b/ethcore/src/engines/mod.rs
@@ -14,7 +14,13 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
-//! Consensus engine specification
+//! Consensus engine specification and basic implementations.
+
+mod null_engine;
+mod basic_authority;
+
+pub use self::null_engine::NullEngine;
+pub use self::basic_authority::BasicAuthority;
 
 use common::*;
 use account_provider::AccountProvider;
diff --git a/ethcore/src/null_engine.rs b/ethcore/src/engines/null_engine.rs
similarity index 93%
rename from ethcore/src/null_engine.rs
rename to ethcore/src/engines/null_engine.rs
index a760bea93..aebf7d1bf 100644
--- a/ethcore/src/null_engine.rs
+++ b/ethcore/src/engines/null_engine.rs
@@ -17,12 +17,12 @@
 use std::collections::BTreeMap;
 use util::hash::Address;
 use builtin::Builtin;
-use engine::Engine;
+use engines::Engine;
 use spec::CommonParams;
 use evm::Schedule;
 use env_info::EnvInfo;
 
-/// An engine which does not provide any consensus mechanism.
+/// An engine which does not provide any consensus mechanism and does not seal blocks.
 pub struct NullEngine {
 	params: CommonParams,
 	builtins: BTreeMap<Address, Builtin>,
diff --git a/ethcore/src/ethereum/ethash.rs b/ethcore/src/ethereum/ethash.rs
index 802b68e82..2a0f84c23 100644
--- a/ethcore/src/ethereum/ethash.rs
+++ b/ethcore/src/ethereum/ethash.rs
@@ -18,7 +18,7 @@ use ethash::{quick_get_difficulty, EthashManager, H256 as EH256};
 use common::*;
 use block::*;
 use spec::CommonParams;
-use engine::*;
+use engines::Engine;
 use evm::Schedule;
 use ethjson;
 
diff --git a/ethcore/src/executive.rs b/ethcore/src/executive.rs
index 5a7d6da10..9a48f9d4a 100644
--- a/ethcore/src/executive.rs
+++ b/ethcore/src/executive.rs
@@ -17,7 +17,7 @@
 //! Transaction Execution environment.
 use common::*;
 use state::*;
-use engine::*;
+use engines::Engine;
 use types::executed::CallType;
 use evm::{self, Ext, Factory, Finalize};
 use externalities::*;
diff --git a/ethcore/src/externalities.rs b/ethcore/src/externalities.rs
index 47c4d9c60..25fed0176 100644
--- a/ethcore/src/externalities.rs
+++ b/ethcore/src/externalities.rs
@@ -17,7 +17,7 @@
 //! Transaction Execution environment.
 use common::*;
 use state::*;
-use engine::*;
+use engines::Engine;
 use executive::*;
 use evm::{self, Schedule, Ext, ContractCreateResult, MessageCallResult, Factory};
 use substate::*;
@@ -300,7 +300,7 @@ impl<'a, T, V> Ext for Externalities<'a, T, V> where T: 'a + Tracer, V: 'a + VMT
 mod tests {
 	use common::*;
 	use state::*;
-	use engine::*;
+	use engines::Engine;
 	use evm::{Ext};
 	use substate::*;
 	use tests::helpers::*;
diff --git a/ethcore/src/json_tests/executive.rs b/ethcore/src/json_tests/executive.rs
index dd6573a37..f1be3e4e0 100644
--- a/ethcore/src/json_tests/executive.rs
+++ b/ethcore/src/json_tests/executive.rs
@@ -17,7 +17,7 @@
 use super::test_common::*;
 use state::*;
 use executive::*;
-use engine::*;
+use engines::Engine;
 use evm;
 use evm::{Schedule, Ext, Factory, Finalize, VMType, ContractCreateResult, MessageCallResult};
 use externalities::*;
diff --git a/ethcore/src/lib.rs b/ethcore/src/lib.rs
index 147232683..3c6f319a1 100644
--- a/ethcore/src/lib.rs
+++ b/ethcore/src/lib.rs
@@ -99,7 +99,7 @@ extern crate ethcore_devtools as devtools;
 #[cfg(feature = "jit" )] extern crate evmjit;
 
 pub mod account_provider;
-pub mod basic_authority;
+pub mod engines;
 pub mod block;
 pub mod block_queue;
 pub mod client;
@@ -111,7 +111,6 @@ pub mod trace;
 pub mod spec;
 pub mod views;
 pub mod pod_state;
-pub mod engine;
 pub mod migrations;
 pub mod miner;
 pub mod snapshot;
@@ -127,7 +126,6 @@ mod pod_account;
 mod state;
 mod account;
 mod account_db;
-mod null_engine;
 mod builtin;
 mod substate;
 mod executive;
diff --git a/ethcore/src/migrations/mod.rs b/ethcore/src/migrations/mod.rs
index 391e5e2f2..e3e1f4031 100644
--- a/ethcore/src/migrations/mod.rs
+++ b/ethcore/src/migrations/mod.rs
@@ -1,3 +1,19 @@
+// Copyright 2015, 2016 Ethcore (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
 //! Database migrations.
 
 pub mod state;
diff --git a/ethcore/src/miner/miner.rs b/ethcore/src/miner/miner.rs
index 79c8a95bf..3edf56a3b 100644
--- a/ethcore/src/miner/miner.rs
+++ b/ethcore/src/miner/miner.rs
@@ -29,7 +29,7 @@ use error::*;
 use transaction::SignedTransaction;
 use receipt::Receipt;
 use spec::Spec;
-use engine::Engine;
+use engines::Engine;
 use miner::{MinerService, MinerStatus, TransactionQueue, AccountDetails, TransactionOrigin};
 use miner::work_notify::WorkPoster;
 use client::TransactionImportResult;
diff --git a/ethcore/src/spec/spec.rs b/ethcore/src/spec/spec.rs
index 3daf096fb..6a9223a1c 100644
--- a/ethcore/src/spec/spec.rs
+++ b/ethcore/src/spec/spec.rs
@@ -17,14 +17,12 @@
 //! Parameters for a block chain.
 
 use common::*;
-use engine::*;
+use engines::{Engine, NullEngine, BasicAuthority};
 use pod_state::*;
-use null_engine::*;
 use account_db::*;
 use super::genesis::Genesis;
 use super::seal::Generic as GenericSeal;
 use ethereum;
-use basic_authority::BasicAuthority;
 use ethjson;
 
 /// Parameters common to all engines.
diff --git a/ethcore/src/state.rs b/ethcore/src/state.rs
index 1da70df3a..45a88d519 100644
--- a/ethcore/src/state.rs
+++ b/ethcore/src/state.rs
@@ -15,7 +15,7 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 use common::*;
-use engine::Engine;
+use engines::Engine;
 use executive::{Executive, TransactOptions};
 use evm::Factory as EvmFactory;
 use account_db::*;
diff --git a/ethcore/src/tests/helpers.rs b/ethcore/src/tests/helpers.rs
index 6e94d2ee3..fe717aa09 100644
--- a/ethcore/src/tests/helpers.rs
+++ b/ethcore/src/tests/helpers.rs
@@ -21,7 +21,7 @@ use block::{OpenBlock, Drain};
 use blockchain::{BlockChain, Config as BlockChainConfig};
 use state::*;
 use evm::Schedule;
-use engine::*;
+use engines::Engine;
 use ethereum;
 use devtools::*;
 use miner::Miner;
diff --git a/ethcore/src/verification/canon_verifier.rs b/ethcore/src/verification/canon_verifier.rs
index e0ebf1b7c..cc6bc448a 100644
--- a/ethcore/src/verification/canon_verifier.rs
+++ b/ethcore/src/verification/canon_verifier.rs
@@ -15,7 +15,7 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 use blockchain::BlockProvider;
-use engine::Engine;
+use engines::Engine;
 use error::Error;
 use header::Header;
 use super::Verifier;
diff --git a/ethcore/src/verification/noop_verifier.rs b/ethcore/src/verification/noop_verifier.rs
index 99d1d594c..fb798be46 100644
--- a/ethcore/src/verification/noop_verifier.rs
+++ b/ethcore/src/verification/noop_verifier.rs
@@ -15,7 +15,7 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 use blockchain::BlockProvider;
-use engine::Engine;
+use engines::Engine;
 use error::Error;
 use header::Header;
 use super::Verifier;
diff --git a/ethcore/src/verification/verification.rs b/ethcore/src/verification/verification.rs
index d3e782764..f0f67c4c2 100644
--- a/ethcore/src/verification/verification.rs
+++ b/ethcore/src/verification/verification.rs
@@ -22,7 +22,7 @@
 /// 3. Final verification against the blockchain done before enactment.
 
 use common::*;
-use engine::Engine;
+use engines::Engine;
 use blockchain::*;
 
 /// Preprocessed block data gathered in `verify_block_unordered` call
@@ -233,7 +233,7 @@ mod tests {
 	use error::BlockError::*;
 	use views::*;
 	use blockchain::*;
-	use engine::*;
+	use engines::Engine;
 	use spec::*;
 	use transaction::*;
 	use tests::helpers::*;
diff --git a/ethcore/src/verification/verifier.rs b/ethcore/src/verification/verifier.rs
index 5db81a4eb..7f57407f7 100644
--- a/ethcore/src/verification/verifier.rs
+++ b/ethcore/src/verification/verifier.rs
@@ -15,7 +15,7 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 use blockchain::BlockProvider;
-use engine::Engine;
+use engines::Engine;
 use error::Error;
 use header::Header;