diff --git a/eth/main.cpp b/eth/main.cpp
index 8bbec9f00..4a8501a97 100644
--- a/eth/main.cpp
+++ b/eth/main.cpp
@@ -1311,7 +1311,7 @@ int main(int argc, char** argv)
 		{
 			try
 			{
-				CanonBlockChain::setGenesisNonce(Nonce(argv[++i]));
+				CanonBlockChain<Ethash>::setGenesisNonce(Nonce(argv[++i]));
 			}
 			catch (...)
 			{
diff --git a/ethminer/MinerAux.h b/ethminer/MinerAux.h
index 0d227b1ef..01083012f 100644
--- a/ethminer/MinerAux.h
+++ b/ethminer/MinerAux.h
@@ -397,17 +397,16 @@ public:
 private:
 	void doInitDAG(unsigned _n)
 	{
-		BlockInfo bi;
-		bi.number() = _n;
-		cout << "Initializing DAG for epoch beginning #" << (bi.number() / 30000 * 30000) << " (seedhash " << bi.proofCache().abridged() << "). This will take a while." << endl;
-		Ethash::prep(bi);
+		h256 seedHash = EthashAux::seedHash(_n);
+		cout << "Initializing DAG for epoch beginning #" << (_n / 30000 * 30000) << " (seedhash " << seedHash.abridged() << "). This will take a while." << endl;
+		EthashAux::full(seedHash, true);
 		exit(0);
 	}
 
 	void doBenchmark(MinerType _m, bool _phoneHome, unsigned _warmupDuration = 15, unsigned _trialDuration = 3, unsigned _trials = 5)
 	{
-		BlockInfo genesis;
-		genesis.difficulty = 1 << 18;
+		Ethash::BlockHeader genesis;
+		genesis.setDifficulty(1 << 18);
 		cdebug << genesis.boundary();
 
 		GenericFarm<EthashProofOfWork> f;
@@ -417,17 +416,16 @@ private:
 		cout << "Benchmarking on platform: " << platformInfo << endl;
 
 		cout << "Preparing DAG..." << endl;
-		Ethash::prep(genesis);
+		genesis.prep();
 
-		genesis.difficulty = u256(1) << 63;
-		genesis.noteDirty();
+		genesis.setDifficulty(u256(1) << 63);
 		f.setWork(genesis);
 		if (_m == MinerType::CPU)
-			f.startCPU();
+			f.start("cpu");
 		else if (_m == MinerType::GPU)
-			f.startGPU();
+			f.start("opencl");
 
-		map<uint64_t, MiningProgress> results;
+		map<uint64_t, WorkingProgress> results;
 		uint64_t mean = 0;
 		uint64_t innerMean = 0;
 		for (unsigned i = 0; i <= _trials; ++i)
@@ -488,9 +486,9 @@ private:
 		Farm rpc(client);
 		GenericFarm<EthashProofOfWork> f;
 		if (_m == MinerType::CPU)
-			f.startCPU();
+			f.start("cpu");
 		else if (_m == MinerType::GPU)
-			f.startGPU();
+			f.start("opencl");
 
 		EthashProofOfWork::WorkPackage current;
 		EthashAux::FullType dag;
diff --git a/libethcore/BlockInfo.h b/libethcore/BlockInfo.h
index 67a5397f4..c310b3dd9 100644
--- a/libethcore/BlockInfo.h
+++ b/libethcore/BlockInfo.h
@@ -128,6 +128,7 @@ public:
 	void setGasUsed(u256 const& _v) { m_gasUsed = _v; noteDirty(); }
 	void setExtraData(bytes const& _v) { m_extraData = _v; noteDirty(); }
 	void setLogBloom(LogBloom const& _v) { m_logBloom = _v; noteDirty(); }
+	void setDifficulty(u256 const& _v) { m_difficulty = _v; noteDirty(); }
 
 	Address const& coinbaseAddress() const { return m_coinbaseAddress; }
 	h256 const& stateRoot() const { return m_stateRoot; }
diff --git a/libethereum/Client.h b/libethereum/Client.h
index 73609bd71..4523d324b 100644
--- a/libethereum/Client.h
+++ b/libethereum/Client.h
@@ -77,7 +77,7 @@ std::ostream& operator<<(std::ostream& _out, ActivityReport const& _r);
  * @brief Main API hub for interfacing with Ethereum.
  * Not to be used directly - subclass.
  */
-class Client: public ClientBase, Worker
+class Client: public ClientBase, protected Worker
 {
 public:
 	/// New-style Constructor.
@@ -342,6 +342,8 @@ public:
 		init(_host, _dbPath, _forceAction, _networkId);
 	}
 
+	virtual ~SpecialisedClient() { stopWorking(); }
+
 	/// Get the object representing the current canonical blockchain.
 	CanonBlockChain<Sealer> const& blockChain() const { return m_bc; }
 
@@ -365,6 +367,8 @@ public:
 		u256 _networkId = 0
 	): SpecialisedClient<Ethash>(_host, _gpForAdoption, _dbPath, _forceAction, _networkId) {}
 
+	virtual ~EthashClient() { stopWorking(); }
+
 	/// Update to the latest transactions and get hash of the current block to be mined minus the
 	/// nonce (the 'work hash') and the difficulty to be met.
 	virtual std::tuple<h256, h256, h256> getEthashWork() override;
diff --git a/test/TestHelper.cpp b/test/TestHelper.cpp
index 30f323369..c29788b9f 100644
--- a/test/TestHelper.cpp
+++ b/test/TestHelper.cpp
@@ -23,6 +23,7 @@
 
 #include <thread>
 #include <chrono>
+#include <libethcore/EthashAux.h>
 #include <libethereum/Client.h>
 #include <liblll/Compiler.h>
 #include <libevm/VMFactory.h>
@@ -63,11 +64,17 @@ void connectClients(Client& c1, Client& c2)
 void mine(State& s, BlockChain const& _bc)
 {
 	s.commitToMine(_bc);
-	GenericFarm<Ethash> f;
+	GenericFarm<EthashProofOfWork> f;
 	bool completed = false;
-	f.onSolutionFound([&](ProofOfWork::Solution sol)
+	Ethash::BlockHeader header(s.info);
+	f.onSolutionFound([&](EthashProofOfWork::Solution sol)
 	{
-		return completed = s.completeMine<ProofOfWork>(sol);
+			header.m_mixHash = sol.mixHash;
+			header.m_nonce = sol.nonce;
+			RLPStream ret;
+			header.streamRLP(ret);
+			s.sealBlock(ret);
+			return true;
 	});
 	f.setWork(s.info());
 	f.startCPU();
@@ -77,9 +84,9 @@ void mine(State& s, BlockChain const& _bc)
 
 void mine(BlockInfo& _bi)
 {
-	GenericFarm<ProofOfWork> f;
+	GenericFarm<EthashProofOfWork> f;
 	bool completed = false;
-	f.onSolutionFound([&](ProofOfWork::Solution sol)
+	f.onSolutionFound([&](EthashProofOfWork::Solution sol)
 	{
 		_bi.proof = sol;
 		return completed = true;
diff --git a/test/libethcore/dagger.cpp b/test/libethcore/dagger.cpp
index 8d4cba933..c3cd75b0d 100644
--- a/test/libethcore/dagger.cpp
+++ b/test/libethcore/dagger.cpp
@@ -58,7 +58,7 @@ BOOST_AUTO_TEST_CASE(basic_test)
 		h256 headerHash(o["header_hash"].get_str());
 		Nonce nonce(o["nonce"].get_str());
 		BOOST_REQUIRE_EQUAL(headerHash, header.hashWithout());
-		BOOST_REQUIRE_EQUAL(nonce, header.nonce);
+		BOOST_REQUIRE_EQUAL(nonce, header.nonce());
 
 		unsigned cacheSize(o["cache_size"].get_int());
 		h256 cacheHash(o["cache_hash"].get_str());
@@ -73,9 +73,9 @@ BOOST_AUTO_TEST_CASE(basic_test)
 #endif
 
 		h256 result(o["result"].get_str());
-		EthashProofOfWork::Result r = EthashAux::eval(header);
+		EthashProofOfWork::Result r = EthashAux::eval(header.seedHash(), header.hashWithout(), header.nonce());
 		BOOST_REQUIRE_EQUAL(r.value, result);
-		BOOST_REQUIRE_EQUAL(r.mixHash, header.mixHash);
+		BOOST_REQUIRE_EQUAL(r.mixHash, header.mixHash());
 	}
 }
 
diff --git a/test/libethereum/ClientBase.cpp b/test/libethereum/ClientBase.cpp
index a426ff53f..f9d83e9c6 100644
--- a/test/libethereum/ClientBase.cpp
+++ b/test/libethereum/ClientBase.cpp
@@ -100,7 +100,7 @@ BOOST_AUTO_TEST_CASE(blocks)
 			ETH_CHECK_EQUAL(expectedHashFromNumber, hashFromNumber);
 			
 			// blockInfo
-			auto compareBlockInfos = [](Json::Value const& _b, BlockInfo _blockInfo) -> void
+			auto compareBlockInfos = [](Json::Value const& _b, Ethash::BlockHeader _blockInfo) -> void
 			{
 				LogBloom expectedBlockInfoBloom = LogBloom(fromHex(_b["bloom"].asString()));
 				Address expectedBlockInfoCoinbase = Address(fromHex(_b["coinbase"].asString()));
@@ -139,7 +139,7 @@ BOOST_AUTO_TEST_CASE(blocks)
 				ETH_CHECK_EQUAL(expectedBlockInfoUncldeHash, _blockInfo.sha3Uncles());
 			};
 
-			BlockInfo blockInfo = _client.blockInfo(blockHash);
+			Ethash::BlockHeader blockInfo(_client.bc().headerData(blockHash));
 			compareBlockInfos(blockHeader, blockInfo);
 
 			// blockDetails
diff --git a/test/libethereum/gaspricer.cpp b/test/libethereum/gaspricer.cpp
index ce49a4a20..050ab2d25 100644
--- a/test/libethereum/gaspricer.cpp
+++ b/test/libethereum/gaspricer.cpp
@@ -20,6 +20,7 @@
  */
 
 #include <libtestutils/BlockChainLoader.h>
+#include <libethcore/Ethash.h>
 #include <libethereum/BlockChain.h>
 #include <libethereum/GasPricer.h>
 #include <libethereum/BasicGasPricer.h>
@@ -54,7 +55,7 @@ BOOST_AUTO_TEST_CASE(trivialGasPricer)
 	std::shared_ptr<dev::eth::GasPricer> gp(new TrivialGasPricer);
 	BOOST_CHECK_EQUAL(gp->ask(State()), 10 * szabo);
 	BOOST_CHECK_EQUAL(gp->bid(), 10 * szabo);
-	gp->update(BlockChain(bytes(), TransientDirectory().path(), WithExisting::Kill));
+	gp->update(FullBlockChain<Ethash>(bytes(), StateDefinition(), TransientDirectory().path(), WithExisting::Kill));
 	BOOST_CHECK_EQUAL(gp->ask(State()), 10 * szabo);
 	BOOST_CHECK_EQUAL(gp->bid(), 10 * szabo);
 }
diff --git a/test/libevm/vm.cpp b/test/libevm/vm.cpp
index 28b2e43ab..badabd70c 100644
--- a/test/libevm/vm.cpp
+++ b/test/libevm/vm.cpp
@@ -33,7 +33,7 @@ using namespace dev::eth;
 using namespace dev::test;
 
 FakeExtVM::FakeExtVM(eth::BlockInfo const& _previousBlock, eth::BlockInfo const& _currentBlock, unsigned _depth):			/// TODO: XXX: remove the default argument & fix.
-	ExtVMFace(Address(), Address(), Address(), 0, 1, bytesConstRef(), bytes(), EmptySHA3, _previousBlock, _currentBlock, test::lastHashes(_currentBlock.number), _depth) {}
+	ExtVMFace(Address(), Address(), Address(), 0, 1, bytesConstRef(), bytes(), EmptySHA3, _previousBlock, _currentBlock, test::lastHashes(_currentBlock.number()), _depth) {}
 
 h160 FakeExtVM::create(u256 _endowment, u256& io_gas, bytesConstRef _init, OnOpFunc const&)
 {
@@ -84,11 +84,11 @@ mObject FakeExtVM::exportEnv()
 {
 	mObject ret;
 	ret["previousHash"] = toString(currentBlock.parentHash());
-	ret["currentDifficulty"] = toCompactHex(currentBlock.difficulty, HexPrefix::Add, 1);
+	ret["currentDifficulty"] = toCompactHex(currentBlock.difficulty(), HexPrefix::Add, 1);
 	ret["currentTimestamp"] =  toCompactHex(currentBlock.timestamp(), HexPrefix::Add, 1);
 	ret["currentCoinbase"] = toString(currentBlock.coinbaseAddress());
-	ret["currentNumber"] = toCompactHex(currentBlock.number, HexPrefix::Add, 1);
-	ret["currentGasLimit"] = toCompactHex(currentBlock.gasLimit, HexPrefix::Add, 1);
+	ret["currentNumber"] = toCompactHex(currentBlock.number(), HexPrefix::Add, 1);
+	ret["currentGasLimit"] = toCompactHex(currentBlock.gasLimit(), HexPrefix::Add, 1);
 	return ret;
 }
 
@@ -107,7 +107,7 @@ void FakeExtVM::importEnv(mObject& _o)
 	lastHashes = test::lastHashes(currentBlock.number);
 	currentBlock.gasLimit = toInt(_o["currentGasLimit"]);
 	currentBlock.difficulty = toInt(_o["currentDifficulty"]);
-	currentBlock.timestamp() = toInt(_o["currentTimestamp"]);
+	currentBlock.timestamp = toInt(_o["currentTimestamp"]);
 	currentBlock.coinbaseAddress() = Address(_o["currentCoinbase"].get_str());
 }