diff --git a/include/libtorrent/add_torrent_params.hpp b/include/libtorrent/add_torrent_params.hpp
index 6e1d7246d..d0d8c5e13 100644
--- a/include/libtorrent/add_torrent_params.hpp
+++ b/include/libtorrent/add_torrent_params.hpp
@@ -77,7 +77,7 @@ namespace libtorrent
 		// The constructor can be used to initialize the storage constructor,
 		// which determines the storage mechanism for the downloaded or seeding
 		// data for the torrent. For more information, see the ``storage`` field.
-		add_torrent_params(storage_constructor_type sc = default_storage_constructor)
+		explicit add_torrent_params(storage_constructor_type sc = default_storage_constructor)
 			: version(LIBTORRENT_VERSION_NUM)
 			, storage_mode(storage_mode_sparse)
 			, storage(sc)
diff --git a/include/libtorrent/alert_types.hpp b/include/libtorrent/alert_types.hpp
index 917c098c6..ec20340ee 100644
--- a/include/libtorrent/alert_types.hpp
+++ b/include/libtorrent/alert_types.hpp
@@ -1674,7 +1674,7 @@ namespace libtorrent
 	struct TORRENT_EXPORT dht_bootstrap_alert final : alert
 	{
 		// internal
-		dht_bootstrap_alert(aux::stack_allocator& alloc);
+		explicit dht_bootstrap_alert(aux::stack_allocator& alloc);
 
 		TORRENT_DEFINE_ALERT(dht_bootstrap_alert, 62)
 
diff --git a/include/libtorrent/announce_entry.hpp b/include/libtorrent/announce_entry.hpp
index 866aa19e4..cd324d4e5 100644
--- a/include/libtorrent/announce_entry.hpp
+++ b/include/libtorrent/announce_entry.hpp
@@ -47,7 +47,7 @@ namespace libtorrent
 	struct TORRENT_EXPORT announce_entry
 	{
 		// constructs a tracker announce entry with ``u`` as the URL.
-		announce_entry(std::string u);
+		explicit announce_entry(std::string u);
 		announce_entry();
 		~announce_entry();
 		announce_entry(announce_entry const&) = default;
diff --git a/include/libtorrent/aux_/bind_to_device.hpp b/include/libtorrent/aux_/bind_to_device.hpp
index 2a1742831..e141f460e 100644
--- a/include/libtorrent/aux_/bind_to_device.hpp
+++ b/include/libtorrent/aux_/bind_to_device.hpp
@@ -47,7 +47,7 @@ namespace libtorrent { namespace aux {
 
 	struct bind_to_device
 	{
-		bind_to_device(char const* device): m_value(device) {}
+		explicit bind_to_device(char const* device): m_value(device) {}
 		template<class Protocol>
 		int level(Protocol const&) const { return SOL_SOCKET; }
 		template<class Protocol>
@@ -66,7 +66,7 @@ namespace libtorrent { namespace aux {
 
 	struct bind_to_device
 	{
-		bind_to_device(char const* device): m_value(if_nametoindex(device)) {}
+		explicit bind_to_device(char const* device): m_value(if_nametoindex(device)) {}
 		template<class Protocol>
 		int level(Protocol const&) const { return IPPROTO_IP; }
 		template<class Protocol>
@@ -85,7 +85,7 @@ namespace libtorrent { namespace aux {
 
 	struct bind_to_device
 	{
-		bind_to_device(char const* device): m_value(device) {}
+		explicit bind_to_device(char const* device): m_value(device) {}
 		template<class Protocol>
 		int level(Protocol const&) const { return SOL_SOCKET; }
 		template<class Protocol>
diff --git a/include/libtorrent/aux_/has_block.hpp b/include/libtorrent/aux_/has_block.hpp
index 983532711..eac64abdc 100644
--- a/include/libtorrent/aux_/has_block.hpp
+++ b/include/libtorrent/aux_/has_block.hpp
@@ -40,7 +40,7 @@ namespace libtorrent { namespace aux {
 	{
 		has_block(has_block const&) = default;
 
-		has_block(piece_block const& b): block(b) {}
+		explicit has_block(piece_block const& b): block(b) {}
 		bool operator()(pending_block const& pb) const
 		{ return pb.block == block; }
 	private:
diff --git a/include/libtorrent/aux_/proxy_settings.hpp b/include/libtorrent/aux_/proxy_settings.hpp
index 91fffa006..de17a4eea 100644
--- a/include/libtorrent/aux_/proxy_settings.hpp
+++ b/include/libtorrent/aux_/proxy_settings.hpp
@@ -53,8 +53,8 @@ namespace aux {
 
 		// construct the proxy_settings object from the settings
 		// this constructor is implemented in session_impl.cpp
-		proxy_settings(settings_pack const& sett);
-		proxy_settings(aux::session_settings const& sett);
+		explicit proxy_settings(settings_pack const& sett);
+		explicit proxy_settings(aux::session_settings const& sett);
 
 		// the name or IP of the proxy server. ``port`` is the port number the
 		// proxy listens to. If required, ``username`` and ``password`` can be
diff --git a/include/libtorrent/aux_/session_impl.hpp b/include/libtorrent/aux_/session_impl.hpp
index 2df5b88cc..8d66c5c78 100644
--- a/include/libtorrent/aux_/session_impl.hpp
+++ b/include/libtorrent/aux_/session_impl.hpp
@@ -216,7 +216,7 @@ namespace libtorrent
 			typedef std::set<std::shared_ptr<peer_connection>> connection_map;
 			typedef std::unordered_map<sha1_hash, std::shared_ptr<torrent>> torrent_map;
 
-			session_impl(io_service& ios);
+			explicit session_impl(io_service& ios);
 			virtual ~session_impl();
 
 			void start_session(settings_pack pack);
@@ -1238,7 +1238,7 @@ namespace libtorrent
 #ifndef TORRENT_DISABLE_LOGGING
 		struct tracker_logger : request_callback
 		{
-			tracker_logger(session_interface& ses);
+			explicit tracker_logger(session_interface& ses);
 			void tracker_warning(tracker_request const& req
 				, std::string const& str);
 			void tracker_response(tracker_request const&
diff --git a/include/libtorrent/bandwidth_manager.hpp b/include/libtorrent/bandwidth_manager.hpp
index e9b70c72a..37dd90b16 100644
--- a/include/libtorrent/bandwidth_manager.hpp
+++ b/include/libtorrent/bandwidth_manager.hpp
@@ -47,7 +47,7 @@ namespace libtorrent {
 
 struct TORRENT_EXTRA_EXPORT bandwidth_manager
 {
-	bandwidth_manager(int channel);
+	explicit bandwidth_manager(int channel);
 
 	void close();
 
@@ -57,7 +57,7 @@ struct TORRENT_EXTRA_EXPORT bandwidth_manager
 
 	int queue_size() const;
 	std::int64_t queued_bytes() const;
-	
+
 	// non prioritized means that, if there's a line for bandwidth,
 	// others will cut in front of the non-prioritized peers.
 	// this is used by web seeds
diff --git a/include/libtorrent/bitfield.hpp b/include/libtorrent/bitfield.hpp
index 39004db44..9e9adad50 100644
--- a/include/libtorrent/bitfield.hpp
+++ b/include/libtorrent/bitfield.hpp
@@ -57,7 +57,7 @@ namespace libtorrent
 		// from the specified buffer, and ``bits`` number of bits (rounded up to
 		// the nearest byte boundary).
 		bitfield() = default;
-		bitfield(int bits) { resize(bits); }
+		explicit bitfield(int bits) { resize(bits); }
 		bitfield(int bits, bool val) { resize(bits, val); }
 		bitfield(char const* b, int bits) { assign(b, bits); }
 		bitfield(bitfield const& rhs) { assign(rhs.data(), rhs.size()); }
diff --git a/include/libtorrent/block_cache.hpp b/include/libtorrent/block_cache.hpp
index 43dc89b50..ab3ec947d 100644
--- a/include/libtorrent/block_cache.hpp
+++ b/include/libtorrent/block_cache.hpp
@@ -73,7 +73,7 @@ namespace libtorrent
 
 	struct piece_log_t
 	{
-		piece_log_t(int j, int b= -1): job(j), block(b) {}
+		explicit piece_log_t(int j, int b= -1): job(j), block(b) {}
 		int job;
 		int block;
 
diff --git a/include/libtorrent/broadcast_socket.hpp b/include/libtorrent/broadcast_socket.hpp
index 24402461e..a4583a73e 100644
--- a/include/libtorrent/broadcast_socket.hpp
+++ b/include/libtorrent/broadcast_socket.hpp
@@ -60,7 +60,7 @@ namespace libtorrent
 	class TORRENT_EXTRA_EXPORT broadcast_socket
 	{
 	public:
-		broadcast_socket(udp::endpoint const& multicast_endpoint);
+		explicit broadcast_socket(udp::endpoint const& multicast_endpoint);
 		~broadcast_socket() { close(); }
 
 		void open(receive_handler_t const& handler, io_service& ios
@@ -77,7 +77,7 @@ namespace libtorrent
 
 		struct socket_entry
 		{
-			socket_entry(std::shared_ptr<udp::socket> const& s)
+			explicit socket_entry(std::shared_ptr<udp::socket> const& s)
 				: socket(s), broadcast(false) { std::memset(buffer, 0, sizeof(buffer)); }
 			socket_entry(std::shared_ptr<udp::socket> const& s
 				, address_v4 const& mask): socket(s), netmask(mask), broadcast(false)
diff --git a/include/libtorrent/buffer.hpp b/include/libtorrent/buffer.hpp
index 36442e98e..8e26895d6 100644
--- a/include/libtorrent/buffer.hpp
+++ b/include/libtorrent/buffer.hpp
@@ -62,7 +62,7 @@ class buffer
 public:
 
 	// allocate an uninitialized buffer of the specified size
-	buffer(std::size_t size = 0)
+	explicit buffer(std::size_t size = 0)
 	{
 		TORRENT_ASSERT(size < std::size_t((std::numeric_limits<std::int32_t>::max)()));
 
diff --git a/include/libtorrent/copy_ptr.hpp b/include/libtorrent/copy_ptr.hpp
index 084f41a64..73c0d2e2b 100644
--- a/include/libtorrent/copy_ptr.hpp
+++ b/include/libtorrent/copy_ptr.hpp
@@ -39,7 +39,7 @@ namespace libtorrent
 	struct copy_ptr
 	{
 		copy_ptr(): m_ptr(0) {}
-		copy_ptr(T* t): m_ptr(t) {}
+		explicit copy_ptr(T* t): m_ptr(t) {}
 		copy_ptr(copy_ptr const& p): m_ptr(p.m_ptr ? new T(*p.m_ptr) : 0) {}
 		void reset(T* t = 0) { delete m_ptr; m_ptr = t; }
 		copy_ptr& operator=(copy_ptr const& p)
diff --git a/include/libtorrent/create_torrent.hpp b/include/libtorrent/create_torrent.hpp
index d319fdb19..ae4683073 100644
--- a/include/libtorrent/create_torrent.hpp
+++ b/include/libtorrent/create_torrent.hpp
@@ -171,7 +171,7 @@ namespace libtorrent
 		explicit create_torrent(file_storage& fs, int piece_size = 0
 			, int pad_file_limit = -1, int flags = optimize_alignment
 			, int alignment = -1);
-		create_torrent(torrent_info const& ti);
+		explicit create_torrent(torrent_info const& ti);
 
 		// internal
 		~create_torrent();
diff --git a/include/libtorrent/entry.hpp b/include/libtorrent/entry.hpp
index 0b6474ef9..89c3ff9c3 100644
--- a/include/libtorrent/entry.hpp
+++ b/include/libtorrent/entry.hpp
@@ -109,14 +109,14 @@ namespace libtorrent
 		// as a key, sorting would become a problem (e.g. to compare a string
 		// to a list). The definition doesn't mention such a limit though.
 #if __cplusplus <= 201103
-		typedef std::map<std::string, entry> dictionary_type;
+		using dictionary_type = std::map<std::string, entry>;
 #else
-		typedef std::map<std::string, entry, aux::strview_less> dictionary_type;
+		using dictionary_type = std::map<std::string, entry, aux::strview_less>;
 #endif
-		typedef std::string string_type;
-		typedef std::vector<entry> list_type;
-		typedef std::int64_t integer_type;
-		typedef std::vector<char> preformatted_type;
+		using string_type = std::string;
+		using list_type = std::vector<entry>;
+		using integer_type = std::int64_t;
+		using preformatted_type = std::vector<char>;
 
 		// the types an entry can have
 		enum data_type
@@ -135,13 +135,13 @@ namespace libtorrent
 		// constructors directly from a specific type.
 		// The content of the argument is copied into the
 		// newly constructed entry
-		entry(dictionary_type);
-		entry(span<char const>);
+		entry(dictionary_type); // NOLINT
+		entry(span<char const>); // NOLINT
 		template <typename U, typename Cond = typename std::enable_if<
 			std::is_same<U, entry::string_type>::value
 			|| std::is_same<U, string_view>::value
 			|| std::is_same<U, char const*>::value>::type>
-		entry(U v)
+		entry(U v) // NOLINT
 			: m_type(undefined_t)
 		{
 #if TORRENT_USE_ASSERTS
@@ -150,13 +150,13 @@ namespace libtorrent
 			new(&data) string_type(std::move(v));
 			m_type = string_t;
 		}
-		entry(list_type);
-		entry(integer_type);
-		entry(preformatted_type);
+		entry(list_type); // NOLINT
+		entry(integer_type); // NOLINT
+		entry(preformatted_type); // NOLINT
 
 		// construct an empty entry of the specified type.
 		// see data_type enum.
-		entry(data_type t);
+		entry(data_type t); // NOLINT
 
 		// hidden
 		entry(entry const& e);
diff --git a/include/libtorrent/error_code.hpp b/include/libtorrent/error_code.hpp
index 3e467e8d4..c57fdd31f 100644
--- a/include/libtorrent/error_code.hpp
+++ b/include/libtorrent/error_code.hpp
@@ -500,7 +500,7 @@ namespace libtorrent
 	struct TORRENT_EXPORT storage_error
 	{
 		storage_error(): file(-1), operation(0) {}
-		storage_error(error_code e): ec(e), file(-1), operation(0) {}
+		explicit storage_error(error_code e): ec(e), file(-1), operation(0) {}
 
 		operator bool() const { return ec.value() != 0; }
 
diff --git a/include/libtorrent/file.hpp b/include/libtorrent/file.hpp
index b0b693672..7e4ba26f6 100644
--- a/include/libtorrent/file.hpp
+++ b/include/libtorrent/file.hpp
@@ -209,7 +209,7 @@ namespace libtorrent
 	struct file_handle
 	{
 		file_handle();
-		file_handle(file* f);
+		explicit file_handle(file* f);
 		file_handle(file_handle const& fh);
 		~file_handle();
 		file* operator->();
diff --git a/include/libtorrent/file_pool.hpp b/include/libtorrent/file_pool.hpp
index 85c2cd723..99cf58338 100644
--- a/include/libtorrent/file_pool.hpp
+++ b/include/libtorrent/file_pool.hpp
@@ -84,7 +84,7 @@ namespace libtorrent
 	{
 		// ``size`` specifies the number of allowed files handles
 		// to hold open at any given time.
-		file_pool(int size = 40);
+		explicit file_pool(int size = 40);
 		~file_pool();
 
 		// return an open file handle to file at ``file_index`` in the
diff --git a/include/libtorrent/hasher.hpp b/include/libtorrent/hasher.hpp
index 34bdb1f6e..fd3bfcf1e 100644
--- a/include/libtorrent/hasher.hpp
+++ b/include/libtorrent/hasher.hpp
@@ -89,7 +89,7 @@ namespace libtorrent
 		// this is the same as default constructing followed by a call to
 		// ``update(data, len)``.
 		hasher(char const* data, int len);
-		hasher(span<char const> data);
+		explicit hasher(span<char const> data);
 		hasher(hasher const&);
 		hasher& operator=(hasher const&);
 
diff --git a/include/libtorrent/heterogeneous_queue.hpp b/include/libtorrent/heterogeneous_queue.hpp
index 170adedd3..2614e06a1 100644
--- a/include/libtorrent/heterogeneous_queue.hpp
+++ b/include/libtorrent/heterogeneous_queue.hpp
@@ -158,7 +158,7 @@ namespace libtorrent {
 			void (*move)(uintptr_t* dst, uintptr_t* src);
 		};
 
-		const static int header_size = (sizeof(header_t) + sizeof(uintptr_t)
+		static int const header_size = (sizeof(header_t) + sizeof(uintptr_t)
 			- 1) / sizeof(uintptr_t);
 
 		void grow_capacity(int const size)
diff --git a/include/libtorrent/http_parser.hpp b/include/libtorrent/http_parser.hpp
index 2ab632543..2736f6fee 100644
--- a/include/libtorrent/http_parser.hpp
+++ b/include/libtorrent/http_parser.hpp
@@ -58,7 +58,7 @@ namespace libtorrent
 	{
 	public:
 		enum flags_t { dont_parse_chunks = 1 };
-		http_parser(int flags = 0);
+		explicit http_parser(int flags = 0);
 		~http_parser();
 		std::string const& header(char const* key) const
 		{
diff --git a/include/libtorrent/i2p_stream.hpp b/include/libtorrent/i2p_stream.hpp
index a699ff304..1f7826820 100644
--- a/include/libtorrent/i2p_stream.hpp
+++ b/include/libtorrent/i2p_stream.hpp
@@ -167,7 +167,7 @@ private:
 class i2p_connection
 {
 public:
-	i2p_connection(io_service& ios);
+	explicit i2p_connection(io_service& ios);
 	~i2p_connection();
 
 	aux::proxy_settings proxy() const;
diff --git a/include/libtorrent/invariant_check.hpp b/include/libtorrent/invariant_check.hpp
index 7859b7fb4..2bbbf15ce 100644
--- a/include/libtorrent/invariant_check.hpp
+++ b/include/libtorrent/invariant_check.hpp
@@ -35,7 +35,7 @@ namespace libtorrent
 	template<class T>
 	struct invariant_checker_impl : invariant_checker
 	{
-		invariant_checker_impl(T const& self_)
+		explicit invariant_checker_impl(T const& self_)
 			: self(self_)
 		{
 			TORRENT_TRY
diff --git a/include/libtorrent/ip_filter.hpp b/include/libtorrent/ip_filter.hpp
index c83936b54..41dd4b29e 100644
--- a/include/libtorrent/ip_filter.hpp
+++ b/include/libtorrent/ip_filter.hpp
@@ -145,8 +145,8 @@ namespace detail
 			TORRENT_ASSERT(!m_access_list.empty());
 			TORRENT_ASSERT(first < last || first == last);
 
-			typename range_t::iterator i = m_access_list.upper_bound(first);
-			typename range_t::iterator j = m_access_list.upper_bound(last);
+			auto i = m_access_list.upper_bound(first);
+			auto j = m_access_list.upper_bound(last);
 
 			if (i != m_access_list.begin()) --i;
 
@@ -198,7 +198,7 @@ namespace detail
 		std::uint32_t access(Addr const& addr) const
 		{
 			TORRENT_ASSERT(!m_access_list.empty());
-			typename range_t::const_iterator i = m_access_list.upper_bound(addr);
+			auto i = m_access_list.upper_bound(addr);
 			if (i != m_access_list.begin()) --i;
 			TORRENT_ASSERT(i != m_access_list.end());
 			TORRENT_ASSERT(i->start <= addr && (std::next(i) == m_access_list.end()
@@ -234,20 +234,17 @@ namespace detail
 
 		struct range
 		{
-			range(Addr addr, int a = 0): start(addr), access(a) {}
-			bool operator<(range const& r) const
-			{ return start < r.start; }
-			bool operator<(Addr const& a) const
-			{ return start < a; }
+			range(Addr addr, int a = 0): start(addr), access(a) {} // NOLINT
+			bool operator<(range const& r) const { return start < r.start; }
+			bool operator<(Addr const& a) const { return start < a; }
 			Addr start;
 			// the end of the range is implicit
 			// and given by the next entry in the set
 			std::uint32_t access;
 		};
 
-		typedef std::set<range> range_t;
+		using range_t = std::set<range>;
 		range_t m_access_list;
-	
 	};
 
 }
diff --git a/include/libtorrent/kademlia/item.hpp b/include/libtorrent/kademlia/item.hpp
index b3dd416ec..65af4060d 100644
--- a/include/libtorrent/kademlia/item.hpp
+++ b/include/libtorrent/kademlia/item.hpp
@@ -77,13 +77,13 @@ class TORRENT_EXTRA_EXPORT item
 public:
 	item() : m_seq(0), m_mutable(false)  {}
 	item(public_key const& pk, span<char const> salt);
-	item(entry v);
+	explicit item(entry v);
 	item(entry v
 		, span<char const> salt
 		, sequence_number seq
 		, public_key const& pk
 		, secret_key const& sk);
-	item(bdecode_node const& v);
+	explicit item(bdecode_node const& v);
 
 	void assign(entry v);
 	void assign(entry v, span<char const> salt
diff --git a/include/libtorrent/kademlia/node_entry.hpp b/include/libtorrent/kademlia/node_entry.hpp
index f838cd2ec..5988e6430 100644
--- a/include/libtorrent/kademlia/node_entry.hpp
+++ b/include/libtorrent/kademlia/node_entry.hpp
@@ -46,7 +46,7 @@ struct TORRENT_EXTRA_EXPORT node_entry
 {
 	node_entry(node_id const& id_, udp::endpoint const& ep, int roundtriptime = 0xffff
 		, bool pinged = false);
-	node_entry(udp::endpoint const& ep);
+	explicit node_entry(udp::endpoint const& ep);
 	node_entry();
 	void update_rtt(int new_rtt);
 
diff --git a/include/libtorrent/linked_list.hpp b/include/libtorrent/linked_list.hpp
index 9b303f169..cffca27c8 100644
--- a/include/libtorrent/linked_list.hpp
+++ b/include/libtorrent/linked_list.hpp
@@ -57,7 +57,7 @@ namespace libtorrent
 		void prev() { m_current = m_current->prev; }
 
 	private:
-		list_iterator(T* cur)
+		explicit list_iterator(T* cur)
 			: m_current(cur) {}
 		// the current element
 		T* m_current;
diff --git a/include/libtorrent/peer_class.hpp b/include/libtorrent/peer_class.hpp
index e196ce7d9..1333d2c9d 100644
--- a/include/libtorrent/peer_class.hpp
+++ b/include/libtorrent/peer_class.hpp
@@ -86,7 +86,7 @@ namespace libtorrent
 	{
 		friend struct peer_class_pool;
 
-		peer_class(std::string const& l)
+		explicit peer_class(std::string const& l)
 			: ignore_unchoke_slots(false)
 			, connection_limit_factor(100)
 			, label(l)
diff --git a/include/libtorrent/peer_connection.hpp b/include/libtorrent/peer_connection.hpp
index d034fc449..0e3976584 100644
--- a/include/libtorrent/peer_connection.hpp
+++ b/include/libtorrent/peer_connection.hpp
@@ -92,7 +92,7 @@ namespace libtorrent
 
 	struct pending_block
 	{
-		pending_block(piece_block const& b)
+		pending_block(piece_block const& b) // NOLINT
 			: block(b), send_buffer_offset(not_in_buffer), not_wanted(false)
 			, timed_out(false), busy(false)
 		{}
@@ -277,7 +277,7 @@ namespace libtorrent
 			num_channels
 		};
 
-		peer_connection(peer_connection_args const& pack);
+		explicit peer_connection(peer_connection_args const& pack);
 
 		// this function is called after it has been constructed and properly
 		// reference counted. It is safe to call self() in this function
@@ -1216,7 +1216,7 @@ namespace libtorrent
 
 	struct cork
 	{
-		cork(peer_connection& p): m_pc(p), m_need_uncork(false)
+		explicit cork(peer_connection& p): m_pc(p)
 		{
 			if (m_pc.is_corked()) return;
 			m_pc.cork_socket();
@@ -1225,7 +1225,7 @@ namespace libtorrent
 		~cork() { if (m_need_uncork) m_pc.uncork_socket(); }
 	private:
 		peer_connection& m_pc;
-		bool m_need_uncork;
+		bool m_need_uncork = false;
 
 		cork& operator=(cork const&);
 	};
diff --git a/include/libtorrent/peer_connection_handle.hpp b/include/libtorrent/peer_connection_handle.hpp
index 2e5d9760f..6d55fdee3 100644
--- a/include/libtorrent/peer_connection_handle.hpp
+++ b/include/libtorrent/peer_connection_handle.hpp
@@ -51,7 +51,7 @@ struct crypto_plugin;
 
 struct TORRENT_EXPORT peer_connection_handle
 {
-	peer_connection_handle(std::weak_ptr<peer_connection> impl)
+	explicit peer_connection_handle(std::weak_ptr<peer_connection> impl)
 		: m_connection(impl)
 	{}
 
diff --git a/include/libtorrent/piece_picker.hpp b/include/libtorrent/piece_picker.hpp
index 241f1cf8c..598a2a2b1 100644
--- a/include/libtorrent/piece_picker.hpp
+++ b/include/libtorrent/piece_picker.hpp
@@ -418,7 +418,7 @@ namespace libtorrent
 		// functor that compares indices on downloading_pieces
 		struct has_index
 		{
-			has_index(int i): index(std::uint32_t(i)) { TORRENT_ASSERT(i >= 0); }
+			explicit has_index(int i): index(std::uint32_t(i)) { TORRENT_ASSERT(i >= 0); }
 			bool operator()(const downloading_piece& p) const
 			{ return p.index == index; }
 			std::uint32_t index;
diff --git a/include/libtorrent/receive_buffer.hpp b/include/libtorrent/receive_buffer.hpp
index 3c30f132f..72f40b96d 100644
--- a/include/libtorrent/receive_buffer.hpp
+++ b/include/libtorrent/receive_buffer.hpp
@@ -167,7 +167,7 @@ private:
 // tracks the state of the bittorrent protocol.
 struct crypto_receive_buffer
 {
-	crypto_receive_buffer(receive_buffer& next)
+	explicit crypto_receive_buffer(receive_buffer& next)
 		: m_connection_buffer(next)
 	{}
 
diff --git a/include/libtorrent/resolve_links.hpp b/include/libtorrent/resolve_links.hpp
index df3649432..5ed1109ae 100644
--- a/include/libtorrent/resolve_links.hpp
+++ b/include/libtorrent/resolve_links.hpp
@@ -57,7 +57,7 @@ namespace libtorrent
 			int file_idx;
 		};
 
-		resolve_links(std::shared_ptr<torrent_info> ti);
+		explicit resolve_links(std::shared_ptr<torrent_info> ti);
 
 		// check to see if any files are shared with this torrent
 		void match(std::shared_ptr<const torrent_info> const& ti
diff --git a/include/libtorrent/resolver.hpp b/include/libtorrent/resolver.hpp
index 1718f9e84..d4d53b305 100644
--- a/include/libtorrent/resolver.hpp
+++ b/include/libtorrent/resolver.hpp
@@ -55,7 +55,7 @@ namespace libtorrent
 
 struct TORRENT_EXTRA_EXPORT resolver final : resolver_interface
 {
-	resolver(io_service& ios);
+	explicit resolver(io_service& ios);
 
 	virtual void async_resolve(std::string const& host, int flags
 		, callback_t const& h) override;
diff --git a/include/libtorrent/session.hpp b/include/libtorrent/session.hpp
index 6fc346dc4..4cd28ea67 100644
--- a/include/libtorrent/session.hpp
+++ b/include/libtorrent/session.hpp
@@ -133,7 +133,7 @@ namespace libtorrent
 		// (ut_metadata, ut_pex and smart_ban). The default values in the
 		// settings is to start the default features like upnp, nat-pmp,
 		// and dht for example.
-		session_params(settings_pack sp = settings_pack());
+		explicit session_params(settings_pack sp = settings_pack());
 		// This constructor helps to configure the set of initial plugins
 		// to be added to the session before it's started.
 		session_params(settings_pack sp
@@ -180,7 +180,7 @@ namespace libtorrent
 		// In order to avoid a race condition between starting the session and
 		// configuring it, you can pass in a session_params object. Its settings
 		// will take effect before the session starts up.
-		session(session_params params = session_params())
+		explicit session(session_params params = session_params())
 			: session_handle(nullptr)
 		{
 			TORRENT_CFG();
diff --git a/include/libtorrent/session_handle.hpp b/include/libtorrent/session_handle.hpp
index bef79b20b..0e5c4b0c1 100644
--- a/include/libtorrent/session_handle.hpp
+++ b/include/libtorrent/session_handle.hpp
@@ -69,7 +69,7 @@ namespace libtorrent
 	{
 		session_handle() : m_impl(nullptr) {}
 
-		session_handle(aux::session_impl* impl)
+		explicit session_handle(aux::session_impl* impl)
 			: m_impl(impl)
 		{}
 
diff --git a/include/libtorrent/socket.hpp b/include/libtorrent/socket.hpp
index c7b62a9cf..8ac85c24d 100644
--- a/include/libtorrent/socket.hpp
+++ b/include/libtorrent/socket.hpp
@@ -94,7 +94,7 @@ namespace libtorrent
 
 	struct v6_protection_level
 	{
-		v6_protection_level(int level): m_value(level) {}
+		explicit v6_protection_level(int level): m_value(level) {}
 		template<class Protocol>
 		int level(Protocol const&) const { return IPPROTO_IPV6; }
 		template<class Protocol>
@@ -108,7 +108,7 @@ namespace libtorrent
 
 	struct exclusive_address_use
 	{
-		exclusive_address_use(int enable): m_value(enable) {}
+		explicit exclusive_address_use(int enable): m_value(enable) {}
 		template<class Protocol>
 		int level(Protocol const&) const { return SOL_SOCKET; }
 		template<class Protocol>
@@ -124,7 +124,7 @@ namespace libtorrent
 #ifdef IPV6_TCLASS
 	struct traffic_class
 	{
-		traffic_class(char val): m_value(val) {}
+		explicit traffic_class(char val): m_value(val) {}
 		template<class Protocol>
 		int level(Protocol const&) const { return IPPROTO_IPV6; }
 		template<class Protocol>
@@ -140,11 +140,11 @@ namespace libtorrent
 	struct type_of_service
 	{
 #ifdef _WIN32
-		typedef DWORD tos_t;
+		using tos_t = DWORD;
 #else
-		typedef int tos_t;
+		using tos_t = int;
 #endif
-		type_of_service(char val): m_value(val) {}
+		explicit type_of_service(char val): m_value(val) {}
 		template<class Protocol>
 		int level(Protocol const&) const { return IPPROTO_IP; }
 		template<class Protocol>
@@ -163,7 +163,7 @@ namespace libtorrent
 #ifdef TORRENT_HAS_DONT_FRAGMENT
 	struct dont_fragment
 	{
-		dont_fragment(bool val)
+		explicit dont_fragment(bool val)
 #ifdef IP_PMTUDISCOVER_DO
 			: m_value(val ? IP_PMTUDISC_DO : IP_PMTUDISC_DONT) {}
 #else
diff --git a/include/libtorrent/span.hpp b/include/libtorrent/span.hpp
index e7bc5ccfa..812a3ee9c 100644
--- a/include/libtorrent/span.hpp
+++ b/include/libtorrent/span.hpp
@@ -46,23 +46,23 @@ namespace libtorrent
 		span() : m_ptr(nullptr), m_len(0) {}
 
 		template <typename U>
-		span(span<U> const& v)
+		span(span<U> const& v) // NOLINT
 			: m_ptr(v.data()), m_len(v.size()) {}
 
-		span(T& p) : m_ptr(&p), m_len(1) {}
-		span(T* p, size_t const l) : m_ptr(p), m_len(l) {}
+		span(T& p) : m_ptr(&p), m_len(1) {} // NOLINT
+		span(T* p, size_t const l) : m_ptr(p), m_len(l) {} // NOLINT
 
 		template <typename U, size_t N>
-		span(std::array<U, N>& arr)
+		span(std::array<U, N>& arr) // NOLINT
 			: m_ptr(arr.data()), m_len(arr.size()) {}
 
 		template <typename U, size_t N>
-		span(U (&arr)[N])
+		span(U (&arr)[N]) // NOLINT
 			: m_ptr(&arr[0]), m_len(N) {}
 
 		// anything with a .data() member function is considered a container
 		template <typename Cont, typename = decltype(std::declval<Cont>().data())>
-		span(Cont& c)
+		span(Cont& c) // NOLINT
 			: m_ptr(c.data()), m_len(c.size()) {}
 
 		size_t size() const { return m_len; }
diff --git a/include/libtorrent/stat_cache.hpp b/include/libtorrent/stat_cache.hpp
index b5d82906a..834fda909 100644
--- a/include/libtorrent/stat_cache.hpp
+++ b/include/libtorrent/stat_cache.hpp
@@ -78,7 +78,7 @@ namespace libtorrent
 
 		struct stat_cache_t
 		{
-			stat_cache_t(std::int64_t s): file_size(s) {}
+			stat_cache_t(std::int64_t s): file_size(s) {} // NOLINT
 
 			// the size of the file. Negative values have special meaning. -1 means
 			// not-in-cache (i.e. there's no data for this file in the cache).
diff --git a/include/libtorrent/storage.hpp b/include/libtorrent/storage.hpp
index 20145bedd..5d1c0a730 100644
--- a/include/libtorrent/storage.hpp
+++ b/include/libtorrent/storage.hpp
@@ -388,7 +388,7 @@ namespace libtorrent
 		// an empty vector. Any file whose index is not represented by the vector
 		// (because the vector is too short) are assumed to have priority 1.
 		// this is used to treat files with priority 0 slightly differently.
-		default_storage(storage_params const& params);
+		explicit default_storage(storage_params const& params);
 
 		// hidden
 		~default_storage();
diff --git a/include/libtorrent/tailqueue.hpp b/include/libtorrent/tailqueue.hpp
index 41bc89cfd..260342158 100644
--- a/include/libtorrent/tailqueue.hpp
+++ b/include/libtorrent/tailqueue.hpp
@@ -61,7 +61,7 @@ namespace libtorrent
 		void next() { m_current = m_current->next; }
 
 	private:
-		tailqueue_iterator(T* cur)
+		explicit tailqueue_iterator(T* cur)
 			: m_current(cur) {}
 		// the current element
 		T* m_current;
diff --git a/include/libtorrent/torrent.hpp b/include/libtorrent/torrent.hpp
index c4f62aa5f..f09d4b071 100644
--- a/include/libtorrent/torrent.hpp
+++ b/include/libtorrent/torrent.hpp
@@ -126,7 +126,7 @@ namespace libtorrent
 	// this is the internal representation of web seeds
 	struct web_seed_t : web_seed_entry
 	{
-		web_seed_t(web_seed_entry const& wse);
+		explicit web_seed_t(web_seed_entry const& wse);
 		web_seed_t(std::string const& url_, web_seed_entry::type_t type_
 			, std::string const& auth_ = std::string()
 			, web_seed_entry::headers_t const& extra_headers_ = web_seed_entry::headers_t());
diff --git a/include/libtorrent/torrent_handle.hpp b/include/libtorrent/torrent_handle.hpp
index ba94a6826..85d9fb1a6 100644
--- a/include/libtorrent/torrent_handle.hpp
+++ b/include/libtorrent/torrent_handle.hpp
@@ -1293,7 +1293,7 @@ namespace libtorrent
 		template<typename Ret, typename Fun, typename... Args>
 		Ret sync_call_ret(Ret def, Fun f, Args&&... a) const;
 
-		torrent_handle(std::weak_ptr<torrent> const& t)
+		explicit torrent_handle(std::weak_ptr<torrent> const& t)
 		{ if (!t.expired()) m_torrent = t; }
 
 		std::weak_ptr<torrent> m_torrent;
diff --git a/include/libtorrent/torrent_info.hpp b/include/libtorrent/torrent_info.hpp
index a3dd31b7d..709f03fe0 100644
--- a/include/libtorrent/torrent_info.hpp
+++ b/include/libtorrent/torrent_info.hpp
@@ -383,7 +383,7 @@ namespace libtorrent
 // ------- start deprecation -------
 // these functions will be removed in a future version
 		TORRENT_DEPRECATED
-		torrent_info(entry const& torrent_file);
+		explicit torrent_info(entry const& torrent_file);
 // ------- end deprecation -------
 #endif
 
diff --git a/include/libtorrent/tracker_manager.hpp b/include/libtorrent/tracker_manager.hpp
index 390cbb68c..c2661adde 100644
--- a/include/libtorrent/tracker_manager.hpp
+++ b/include/libtorrent/tracker_manager.hpp
@@ -250,7 +250,7 @@ namespace libtorrent
 		: std::enable_shared_from_this<timeout_handler>
 		, boost::noncopyable
 	{
-		timeout_handler(io_service& str);
+		explicit timeout_handler(io_service& str);
 
 		void set_timeout(int completion_timeout, int read_timeout);
 		void restart_read_timeout();
diff --git a/include/libtorrent/udp_socket.hpp b/include/libtorrent/udp_socket.hpp
index 697b02023..a6d074544 100644
--- a/include/libtorrent/udp_socket.hpp
+++ b/include/libtorrent/udp_socket.hpp
@@ -50,7 +50,7 @@ namespace libtorrent
 	class TORRENT_EXTRA_EXPORT udp_socket : single_threaded
 	{
 	public:
-		udp_socket(io_service& ios);
+		explicit udp_socket(io_service& ios);
 
 		enum flags_t {
 			peer_connection = 1
diff --git a/include/libtorrent/union_endpoint.hpp b/include/libtorrent/union_endpoint.hpp
index 08a314d09..0f236e181 100644
--- a/include/libtorrent/union_endpoint.hpp
+++ b/include/libtorrent/union_endpoint.hpp
@@ -40,16 +40,8 @@ namespace libtorrent
 {
 	struct union_address
 	{
-		union_address()
-		{
-			*this = address();
-		}
-
-		union_address(address const& a)
-		{
-			*this = a;
-		}
-
+		union_address() { *this = address(); }
+		explicit union_address(address const& a) { *this = a; }
 		union_address& operator=(address const& a)
 		{
 #if TORRENT_USE_IPV6
@@ -106,20 +98,9 @@ namespace libtorrent
 
 	struct union_endpoint
 	{
-		union_endpoint(tcp::endpoint const& ep)
-		{
-			*this = ep;
-		}
-
-		union_endpoint(udp::endpoint const& ep)
-		{
-			*this = ep;
-		}
-
-		union_endpoint()
-		{
-			*this = tcp::endpoint();
-		}
+		explicit union_endpoint(tcp::endpoint const& ep) { *this = ep; }
+		explicit union_endpoint(udp::endpoint const& ep) { *this = ep; }
+		union_endpoint() { *this = tcp::endpoint(); }
 
 		union_endpoint& operator=(udp::endpoint const& ep)
 		{
@@ -128,10 +109,7 @@ namespace libtorrent
 			return *this;
 		}
 
-		operator udp::endpoint() const
-		{
-			return udp::endpoint(addr, port);
-		}
+		operator udp::endpoint() const { return udp::endpoint(addr, port); }
 
 		union_endpoint& operator=(tcp::endpoint const& ep)
 		{
@@ -140,15 +118,8 @@ namespace libtorrent
 			return *this;
 		}
 
-		libtorrent::address address() const
-		{
-			return addr;
-		}
-
-		operator tcp::endpoint() const
-		{
-			return tcp::endpoint(addr, port);
-		}
+		libtorrent::address address() const { return addr; }
+		operator tcp::endpoint() const { return tcp::endpoint(addr, port); }
 
 		union_address addr;
 		std::uint16_t port;
diff --git a/src/peer_connection.cpp b/src/peer_connection.cpp
index 6108f9340..9f4e5844f 100644
--- a/src/peer_connection.cpp
+++ b/src/peer_connection.cpp
@@ -2521,7 +2521,7 @@ namespace libtorrent
 		// if we're disconnecting, we shouldn't add pieces
 		if (!in_req_queue && !m_disconnecting)
 		{
-			for (std::vector<pending_block>::iterator i = m_request_queue.begin()
+			for (auto i = m_request_queue.begin()
 				, end(m_request_queue.end()); i != end; ++i)
 			{
 				if (i->block != b) continue;
diff --git a/src/session_impl.cpp b/src/session_impl.cpp
index f94c24166..4c5fd077d 100644
--- a/src/session_impl.cpp
+++ b/src/session_impl.cpp
@@ -35,7 +35,6 @@ POSSIBILITY OF SUCH DAMAGE.
 #include <ctime>
 #include <algorithm>
 #include <cctype>
-#include <algorithm>
 #include <cstdio> // for snprintf
 #include <cinttypes> // for PRId64 et.al.
 #include <functional>
@@ -82,7 +81,6 @@ const rlim_t rlim_infinity = RLIM_INFINITY;
 #include "libtorrent/kademlia/node_entry.hpp"
 #endif
 #include "libtorrent/enum_net.hpp"
-#include "libtorrent/config.hpp"
 #include "libtorrent/utf8.hpp"
 #include "libtorrent/upnp.hpp"
 #include "libtorrent/natpmp.hpp"
@@ -382,7 +380,8 @@ namespace aux {
 		SSL_CTX *torrent_context = t->ssl_ctx()->native_handle();
 
 		SSL_set_SSL_CTX(s, torrent_context);
-		SSL_set_verify(s, SSL_CTX_get_verify_mode(torrent_context), SSL_CTX_get_verify_callback(torrent_context));
+		SSL_set_verify(s, SSL_CTX_get_verify_mode(torrent_context)
+			, SSL_CTX_get_verify_callback(torrent_context));
 
 		return SSL_TLSEXT_ERR_OK;
 	}
@@ -592,11 +591,13 @@ namespace aux {
 #endif
 		m_io_service.post([this]{ this->wrap(&session_impl::on_tick, error_code()); });
 
+		int const lsd_announce_interval
+			= m_settings.get_int(settings_pack::local_service_announce_interval);
+		int const delay = std::max(lsd_announce_interval
+			/ std::max(static_cast<int>(m_torrents.size()), 1), 1);
 		error_code ec;
-		ADD_OUTSTANDING_ASYNC("session_impl::on_lsd_announce");
-		int const delay = std::max(m_settings.get_int(settings_pack::local_service_announce_interval)
-			/ std::max(int(m_torrents.size()), 1), 1);
 		m_lsd_announce_timer.expires_from_now(seconds(delay), ec);
+		ADD_OUTSTANDING_ASYNC("session_impl::on_lsd_announce");
 		m_lsd_announce_timer.async_wait([this](error_code const& e) {
 			this->wrap(&session_impl::on_lsd_announce, e); } );
 		TORRENT_ASSERT(!ec);
diff --git a/src/torrent.cpp b/src/torrent.cpp
index 68ace0e07..6512a88b4 100644
--- a/src/torrent.cpp
+++ b/src/torrent.cpp
@@ -294,8 +294,9 @@ namespace libtorrent
 
 		int tier = 0;
 		auto tier_iter = p.tracker_tiers.begin();
-		for (announce_entry e : p.trackers)
+		for (auto const& url : p.trackers)
 		{
+			announce_entry e(url);
 			if (tier_iter != p.tracker_tiers.end())
 				tier = *tier_iter++;
 
diff --git a/src/torrent_info.cpp b/src/torrent_info.cpp
index ae7c173be..5bbcba528 100644
--- a/src/torrent_info.cpp
+++ b/src/torrent_info.cpp
@@ -1347,9 +1347,8 @@ namespace libtorrent
 				if (ec) return false;
 
 				m_info_hash = p.info_hash;
-				for (std::vector<std::string>::iterator i = p.trackers.begin()
-					, end(p.trackers.end()); i != end; ++i)
-					m_urls.push_back(*i);
+				for (auto const& url : p.trackers)
+					m_urls.push_back(announce_entry(url));
 
 				return true;
 			}
diff --git a/test/test_dht.cpp b/test/test_dht.cpp
index e89168f31..df16c105e 100644
--- a/test/test_dht.cpp
+++ b/test/test_dht.cpp
@@ -1741,7 +1741,7 @@ void test_bootstrap(address(&rand_addr)())
 
 	udp::endpoint found_node(rand_addr(), 2235);
 	std::vector<node_entry> nodes;
-	nodes.push_back(found_node);
+	nodes.push_back(node_entry{found_node});
 	g_sent_packets.clear();
 	if (initial_node.address().is_v4())
 		send_dht_response(t.dht_node, response, initial_node, msg_args().nodes(nodes));
@@ -1843,7 +1843,7 @@ void test_short_nodes(address(&rand_addr)())
 
 	udp::endpoint found_node(rand_addr(), 2235);
 	std::vector<node_entry> nodes;
-	nodes.push_back(found_node);
+	nodes.push_back(node_entry{found_node});
 	g_sent_packets.clear();
 	msg_args args;
 	// chop one byte off of the nodes string
@@ -1900,7 +1900,7 @@ void test_get_peers(address(&rand_addr)())
 	dht::node_id const target = to_hash("1234876923549721020394873245098347598635");
 
 	udp::endpoint const initial_node(rand_addr(), 1234);
-	t.dht_node.m_table.add_node(initial_node);
+	t.dht_node.m_table.add_node(node_entry{initial_node});
 
 	t.dht_node.announce(target, 1234, false, get_peers_cb);
 
@@ -1933,7 +1933,7 @@ void test_get_peers(address(&rand_addr)())
 
 	udp::endpoint next_node(rand_addr(), 2235);
 	std::vector<node_entry> nodes;
-	nodes.push_back(next_node);
+	nodes.push_back(node_entry{next_node});
 
 	g_sent_packets.clear();
 	if (initial_node.address().is_v4())
@@ -2032,7 +2032,7 @@ void test_mutable_get(address(&rand_addr)(), bool const with_salt)
 	g_sent_packets.clear();
 
 	udp::endpoint const initial_node(rand_addr(), 1234);
-	t.dht_node.m_table.add_node(initial_node);
+	t.dht_node.m_table.add_node(node_entry{initial_node});
 
 	g_put_item.assign(items[0].ent, salt, seq, pk, sk);
 	t.dht_node.put_item(pk, std::string()
@@ -2129,7 +2129,7 @@ TORRENT_TEST(immutable_get)
 	g_sent_packets.clear();
 
 	udp::endpoint initial_node(addr4("4.4.4.4"), 1234);
-	t.dht_node.m_table.add_node(initial_node);
+	t.dht_node.m_table.add_node(node_entry{initial_node});
 
 	t.dht_node.get_item(items[0].target, get_immutable_item_cb);
 
@@ -2960,7 +2960,7 @@ TORRENT_TEST(read_only_node)
 	bdecode_node parsed[7];
 	char error_string[200];
 	udp::endpoint initial_node(addr("4.4.4.4"), 1234);
-	node.m_table.add_node(initial_node);
+	node.m_table.add_node(node_entry{initial_node});
 	bdecode_node request;
 	sha1_hash target = generate_next();
 
diff --git a/test/test_storage.cpp b/test/test_storage.cpp
index ecf07a55f..43c708d85 100644
--- a/test/test_storage.cpp
+++ b/test/test_storage.cpp
@@ -352,7 +352,7 @@ void test_remove(std::string const& test_path, bool unbuffered)
 	TEST_EQUAL(st.file_size, 8);
 
 	s->delete_files(session::delete_files, se);
-	if (se) print_error("delete_files", 0, se.ec);
+	if (se) print_error("delete_files", 0, se);
 
 	if (se)
 	{