diff --git a/alethzero/MainWin.cpp b/alethzero/MainWin.cpp
index d3d3dd129..6ad4b5d87 100644
--- a/alethzero/MainWin.cpp
+++ b/alethzero/MainWin.cpp
@@ -26,7 +26,7 @@ Main::Main(QWidget *parent) :
 	setWindowFlags(Qt::Window);
 	ui->setupUi(this);
 	g_logPost = [=](std::string const& s, char const* c) { simpleDebugOut(s, c); ui->log->addItem(QString::fromStdString(s)); };
-	m_client = new Client("AlethZero");
+	m_client.reset(new Client("AlethZero"));
 
 	readSettings();
 	refresh();
@@ -63,7 +63,6 @@ Main::~Main()
 {
 	g_logPost = simpleDebugOut;
 	writeSettings();
-	delete ui;
 }
 
 void Main::on_about_triggered()
diff --git a/alethzero/MainWin.h b/alethzero/MainWin.h
index 02d3506c4..e1cb44e65 100644
--- a/alethzero/MainWin.h
+++ b/alethzero/MainWin.h
@@ -54,9 +54,9 @@ private:
 	eth::u256 total() const;
 	eth::u256 value() const;
 
-	Ui::Main *ui;
+	std::unique_ptr<Ui::Main> ui;
 
-	eth::Client* m_client;
+	std::unique_ptr<eth::Client> m_client;
 
 	QByteArray m_peers;
 	QMutex m_guiLock;
diff --git a/libethereum/Client.cpp b/libethereum/Client.cpp
index 5f811d1bc..c30de604f 100644
--- a/libethereum/Client.cpp
+++ b/libethereum/Client.cpp
@@ -33,7 +33,8 @@ Client::Client(std::string const& _clientVersion, Address _us, std::string const
 	m_bc(_dbPath),
 	m_stateDB(State::openDB(_dbPath)),
 	m_preMine(_us, m_stateDB),
-	m_postMine(_us, m_stateDB)
+	m_postMine(_us, m_stateDB),
+	m_workState(Active)
 {
 	Defaults::setDBPath(_dbPath);
 
@@ -45,26 +46,28 @@ Client::Client(std::string const& _clientVersion, Address _us, std::string const
 
 	static const char* c_threadName = "eth";
 
-	m_work = new thread([&](){
+	m_work.reset(new thread([&](){
 		setThreadName(c_threadName);
-
-		while (m_workState != Deleting) work(); m_workState = Deleted;
-	});
+		while (m_workState.load(std::memory_order_acquire) != Deleting)
+			work();
+		m_workState.store(Deleted, std::memory_order_release);
+	}));
 }
 
 Client::~Client()
 {
-	if (m_workState == Active)
-		m_workState = Deleting;
-	while (m_workState != Deleted)
+	if (m_workState.load(std::memory_order_acquire) == Active)
+		m_workState.store(Deleting, std::memory_order_release);
+	while (m_workState.load(std::memory_order_acquire) != Deleted)
 		this_thread::sleep_for(chrono::milliseconds(10));
+	m_work->join();
 }
 
 void Client::startNetwork(unsigned short _listenPort, std::string const& _seedHost, unsigned short _port, NodeMode _mode, unsigned _peers, string const& _publicIP, bool _upnp)
 {
-	if (m_net)
+	if (m_net.get())
 		return;
-	m_net = new PeerServer(m_clientVersion, m_bc, 0, _listenPort, _mode, _publicIP, _upnp);
+	m_net.reset(new PeerServer(m_clientVersion, m_bc, 0, _listenPort, _mode, _publicIP, _upnp));
 	m_net->setIdealPeerCount(_peers);
 	if (_seedHost.size())
 		connect(_seedHost, _port);
@@ -72,15 +75,14 @@ void Client::startNetwork(unsigned short _listenPort, std::string const& _seedHo
 
 void Client::connect(std::string const& _seedHost, unsigned short _port)
 {
-	if (!m_net)
+	if (!m_net.get())
 		return;
 	m_net->connect(_seedHost, _port);
 }
 
 void Client::stopNetwork()
 {
-	delete m_net;
-	m_net = nullptr;
+	m_net.reset(nullptr);
 }
 
 void Client::startMining()
diff --git a/libethereum/Client.h b/libethereum/Client.h
index 5c9b64b0f..ab377d73d 100644
--- a/libethereum/Client.h
+++ b/libethereum/Client.h
@@ -23,6 +23,7 @@
 
 #include <thread>
 #include <mutex>
+#include <atomic>
 #include "Common.h"
 #include "BlockChain.h"
 #include "TransactionQueue.h"
@@ -52,6 +53,13 @@ private:
 	Client* m_client;
 };
 
+enum ClientWorkState
+{
+	Active = 0,
+	Deleting,
+	Deleted
+};
+
 class Client
 {
 public:
@@ -112,7 +120,7 @@ public:
 	/// Stop the network subsystem.
 	void stopNetwork();
 	/// Get access to the peer server object. This will be null if the network isn't online.
-	PeerServer* peerServer() const { return m_net; }
+	PeerServer* peerServer() const { return m_net.get(); }
 
 	// Mining stuff:
 
@@ -134,14 +142,14 @@ private:
 	BlockChain m_bc;					///< Maintains block database.
 	TransactionQueue m_tq;				///< Maintains list of incoming transactions not yet on the block chain.
 	Overlay m_stateDB;					///< Acts as the central point for the state database, so multiple States can share it.
-	State m_preMine;							///< The present state of the client.
-	State m_postMine;						///< The state of the client which we're mining (i.e. it'll have all the rewards added).
-	PeerServer* m_net = nullptr;		///< Should run in background and send us events when blocks found and allow us to send blocks as required.
+	State m_preMine;					///< The present state of the client.
+	State m_postMine;					///< The state of the client which we're mining (i.e. it'll have all the rewards added).
+	std::unique_ptr<PeerServer> m_net;	///< Should run in background and send us events when blocks found and allow us to send blocks as required.
 	
-	std::thread* m_work;				///< The work thread.
+	std::unique_ptr<std::thread> m_work;///< The work thread.
 	
 	std::recursive_mutex m_lock;
-	enum { Active = 0, Deleting, Deleted } m_workState = Active;
+	std::atomic<ClientWorkState> m_workState;
 	bool m_doMine = false;				///< Are we supposed to be mining?
 	MineProgress m_mineProgress;
 	mutable bool m_restartMining = false;
diff --git a/libethereum/UPnP.cpp b/libethereum/UPnP.cpp
index 9f6ed4e95..6008bc7de 100644
--- a/libethereum/UPnP.cpp
+++ b/libethereum/UPnP.cpp
@@ -33,8 +33,8 @@ using namespace eth;
 
 UPnP::UPnP()
 {
-	m_urls = new UPNPUrls;
-	m_data = new IGDdatas;
+	m_urls.reset(new UPNPUrls);
+	m_data.reset(new IGDdatas);
 
 	m_ok = false;
 
@@ -43,8 +43,8 @@ UPnP::UPnP()
 	char* descXML;
 	int descXMLsize = 0;
 	int upnperror = 0;
-	memset(m_urls, 0, sizeof(struct UPNPUrls));
-	memset(m_data, 0, sizeof(struct IGDdatas));
+	memset(m_urls.get(), 0, sizeof(struct UPNPUrls));
+	memset(m_data.get(), 0, sizeof(struct IGDdatas));
 	devlist = upnpDiscover(2000, NULL/*multicast interface*/, NULL/*minissdpd socket path*/, 0/*sameport*/, 0/*ipv6*/, &upnperror);
 	if (devlist)
 	{
@@ -66,12 +66,12 @@ UPnP::UPnP()
 #endif
 		if (descXML)
 		{
-			parserootdesc (descXML, descXMLsize, m_data);
+			parserootdesc (descXML, descXMLsize, m_data.get());
 			free (descXML); descXML = 0;
 #if MINIUPNPC_API_VERSION >= 9
-			GetUPNPUrls (m_urls, m_data, dev->descURL, 0);
+			GetUPNPUrls (m_urls.get(), m_data.get(), dev->descURL, 0);
 #else
-			GetUPNPUrls (m_urls, m_data, dev->descURL);
+			GetUPNPUrls (m_urls.get(), m_data.get(), dev->descURL);
 #endif
 			m_ok = true;
 		}
diff --git a/libethereum/UPnP.h b/libethereum/UPnP.h
index bb51c96d1..8713e1d2b 100644
--- a/libethereum/UPnP.h
+++ b/libethereum/UPnP.h
@@ -45,8 +45,8 @@ public:
 
 	std::set<int> m_reg;
 	bool m_ok;
-	struct UPNPUrls* m_urls;
-	struct IGDdatas* m_data;
+	std::unique_ptr<struct UPNPUrls> m_urls;
+	std::unique_ptr<struct IGDdatas> m_data;
 };
 
 }