diff --git a/alethzero/MainWin.cpp b/alethzero/MainWin.cpp
index 2a308e6c9..02e0c56de 100644
--- a/alethzero/MainWin.cpp
+++ b/alethzero/MainWin.cpp
@@ -474,7 +474,7 @@ void Main::refresh(bool _override)
 			int n = 0;
 			for (auto const& i: RLP(bc.block(h))[1])
 			{
-				Transaction t(i.data());
+				Transaction t(i[0].data());
 				QString s = t.receiveAddress ?
 					QString("    %2 %5> %3: %1 [%4]")
 						.arg(formatBalance(t.value).c_str())
@@ -566,7 +566,7 @@ void Main::on_blocks_currentItemChanged()
 		else
 		{
 			unsigned txi = item->data(Qt::UserRole + 1).toInt();
-			Transaction tx(block[1][txi].data());
+			Transaction tx(block[1][txi][0].data());
 			auto ss = tx.safeSender();
 			h256 th = sha3(rlpList(ss, tx.nonce));
 			s << "<h3>" << th << "</h3>";
diff --git a/libethereum/State.cpp b/libethereum/State.cpp
index 4506ee92a..124e02745 100644
--- a/libethereum/State.cpp
+++ b/libethereum/State.cpp
@@ -319,6 +319,7 @@ bool State::sync(TransactionQueue& _tq)
 
 u256 State::playback(bytesConstRef _block, BlockInfo const& _bi, BlockInfo const& _parent, BlockInfo const& _grandParent, bool _fullCommit)
 {
+	resetCurrent();
 	m_currentBlock = _bi;
 	m_previousBlock = _parent;
 	return playbackRaw(_block, _grandParent, _fullCommit);
@@ -342,6 +343,8 @@ u256 State::trustedPlayback(bytesConstRef _block, bool _fullCommit)
 
 u256 State::playbackRaw(bytesConstRef _block, BlockInfo const& _grandParent, bool _fullCommit)
 {
+	// m_currentBlock is assumed to be prepopulated.
+
 	if (m_currentBlock.parentHash != m_previousBlock.hash)
 		throw InvalidParentHash();
 
@@ -350,6 +353,7 @@ u256 State::playbackRaw(bytesConstRef _block, BlockInfo const& _grandParent, boo
 
 	if (_fullCommit)
 		m_transactionManifest.init();
+
 	// All ok with the block generally. Play back the transactions now...
 	unsigned i = 0;
 	for (auto const& tr: RLP(_block)[1])
@@ -357,7 +361,7 @@ u256 State::playbackRaw(bytesConstRef _block, BlockInfo const& _grandParent, boo
 		execute(tr[0].data());
 		if (tr[1].toInt<u256>() != m_state.root())
 			throw InvalidTransactionStateRoot();
-		if (tr[2].toInt<u256>() != m_currentBlock.gasUsed)
+		if (tr[2].toInt<u256>() != gasUsed())
 			throw InvalidTransactionGasUsed();
 		if (_fullCommit)
 		{
@@ -414,14 +418,14 @@ u256 State::playbackRaw(bytesConstRef _block, BlockInfo const& _grandParent, boo
 		m_db.commit();
 
 		m_previousBlock = m_currentBlock;
-		resetCurrent();
 	}
 	else
 	{
 		m_db.rollback();
-		resetCurrent();
 	}
 
+	resetCurrent();
+
 	return tdIncrease;
 }
 
@@ -492,6 +496,7 @@ void State::commitToMine(BlockChain const& _bc)
 //	cnote << m_state;
 //	cnote << *this;
 
+	m_currentBlock.gasUsed = gasUsed();
 	m_currentBlock.stateRoot = m_state.root();
 	m_currentBlock.parentHash = m_previousBlock.hash;
 }
@@ -655,7 +660,8 @@ u256 State::execute(bytesConstRef _rlp)
 	Executive e(*this);
 	e.setup(_rlp);
 
-	if (m_currentBlock.gasUsed + e.t().gas > m_currentBlock.gasLimit)
+	u256 startGasUSed = gasUsed();
+	if (startGasUSed + e.t().gas > m_currentBlock.gasLimit)
 		throw BlockGasLimitReached();	// TODO: make sure this is handled.
 
 	e.go();
@@ -664,8 +670,7 @@ u256 State::execute(bytesConstRef _rlp)
 	commit();
 
 	// Add to the user-originated transactions that we've executed.
-	m_currentBlock.gasUsed += e.gasUsed();
-	m_transactions.push_back(TransactionReceipt(e.t(), m_state.root(), m_currentBlock.gasUsed));
+	m_transactions.push_back(TransactionReceipt(e.t(), m_state.root(), startGasUSed + e.gasUsed()));
 	m_transactionSet.insert(e.t().sha3());
 	return e.gasUsed();
 }
diff --git a/libethereum/State.h b/libethereum/State.h
index 1aa266955..eceb5fe4d 100644
--- a/libethereum/State.h
+++ b/libethereum/State.h
@@ -241,6 +241,8 @@ private:
 	/// Unfinalise the block, unapplying the earned rewards.
 	void unapplyRewards(Addresses const& _uncleAddresses);
 
+	u256 gasUsed() const { return m_transactions.size() ? m_transactions.back().gasUsed : 0; }
+
 	Overlay m_db;								///< Our overlay for the state tree.
 	TrieDB<Address, Overlay> m_state;			///< Our state tree, as an Overlay DB.
 	std::vector<TransactionReceipt> m_transactions;	///< The current list of transactions that we've included in the state.