diff --git a/include/libtorrent/disk_buffer_holder.hpp b/include/libtorrent/disk_buffer_holder.hpp
index e3510a8c0..239a67799 100644
--- a/include/libtorrent/disk_buffer_holder.hpp
+++ b/include/libtorrent/disk_buffer_holder.hpp
@@ -66,10 +66,10 @@ namespace libtorrent
 	struct TORRENT_EXTRA_EXPORT disk_buffer_holder
 	{
 		// internal
-		disk_buffer_holder(buffer_allocator_interface& alloc, char* buf);
+		disk_buffer_holder(buffer_allocator_interface& alloc, char* buf) noexcept;
 
-		disk_buffer_holder& operator=(disk_buffer_holder&&);
-		disk_buffer_holder(disk_buffer_holder&&);
+		disk_buffer_holder& operator=(disk_buffer_holder&&) noexcept;
+		disk_buffer_holder(disk_buffer_holder&&) noexcept;
 
 		disk_buffer_holder& operator=(disk_buffer_holder const&) = delete;
 		disk_buffer_holder(disk_buffer_holder const&) = delete;
@@ -77,7 +77,7 @@ namespace libtorrent
 		// construct a buffer holder that will free the held buffer
 		// using a disk buffer pool directly (there's only one
 		// disk_buffer_pool per session)
-		disk_buffer_holder(buffer_allocator_interface& alloc, disk_io_job const& j);
+		disk_buffer_holder(buffer_allocator_interface& alloc, disk_io_job const& j) noexcept;
 
 		// frees any unreleased disk buffer held by this object
 		~disk_buffer_holder();
@@ -85,10 +85,10 @@ namespace libtorrent
 		// return the held disk buffer and clear it from the
 		// holder. The responsibility to free it is passed on
 		// to the caller
-		char* release();
+		char* release() noexcept;
 
 		// return a pointer to the held buffer
-		char* get() const { return m_buf; }
+		char* get() const noexcept { return m_buf; }
 
 		// set the holder object to hold the specified buffer
 		// (or nullptr by default). If it's already holding a
@@ -97,18 +97,18 @@ namespace libtorrent
 		void reset(disk_io_job const& j);
 
 		// swap pointers of two disk buffer holders.
-		void swap(disk_buffer_holder& h)
+		void swap(disk_buffer_holder& h) noexcept
 		{
 			TORRENT_ASSERT(h.m_allocator == m_allocator);
 			std::swap(h.m_buf, m_buf);
 			std::swap(h.m_ref, m_ref);
 		}
 
-		block_cache_reference ref() const { return m_ref; }
+		block_cache_reference ref() const noexcept { return m_ref; }
 
 		// implicitly convertible to true if the object is currently holding a
 		// buffer
-		explicit operator bool() const { return m_buf != nullptr; }
+		explicit operator bool() const noexcept { return m_buf != nullptr; }
 
 	private:
 
diff --git a/include/libtorrent/tailqueue.hpp b/include/libtorrent/tailqueue.hpp
index 9ecefa0c2..41bc89cfd 100644
--- a/include/libtorrent/tailqueue.hpp
+++ b/include/libtorrent/tailqueue.hpp
@@ -40,7 +40,7 @@ namespace libtorrent
 	template <typename T>
 	struct tailqueue_node
 	{
-		tailqueue_node() : next(0) {}
+		tailqueue_node() : next(nullptr) {}
 		T* next;
 	};
 
@@ -81,12 +81,12 @@ namespace libtorrent
 
 		void append(tailqueue<T>& rhs)
 		{
-			TORRENT_ASSERT(m_last == 0 || m_last->next == 0);
-			TORRENT_ASSERT(rhs.m_last == 0 || rhs.m_last->next == 0);
+			TORRENT_ASSERT(m_last == nullptr || m_last->next == nullptr);
+			TORRENT_ASSERT(rhs.m_last == nullptr || rhs.m_last->next == nullptr);
 
-			if (rhs.m_first == 0) return;
+			if (rhs.m_first == nullptr) return;
 
-			if (m_first == 0)
+			if (m_first == nullptr)
 			{
 				swap(rhs);
 				return;
@@ -95,21 +95,23 @@ namespace libtorrent
 			m_last->next = rhs.m_first;
 			m_last = rhs.m_last;
 			m_size += rhs.m_size;
-			rhs.m_first = 0;
-			rhs.m_last = 0;
+			rhs.m_first = nullptr;
+			rhs.m_last = nullptr;
 			rhs.m_size = 0;
 
-			TORRENT_ASSERT(m_last == 0 || m_last->next == 0);
+			TORRENT_ASSERT(m_last == nullptr || m_last->next == nullptr);
 		}
 
 		void prepend(tailqueue<T>& rhs)
 		{
-			TORRENT_ASSERT(m_last == 0 || m_last->next == 0);
-			TORRENT_ASSERT(rhs.m_last == 0 || rhs.m_last->next == 0);
+			TORRENT_ASSERT(m_last == nullptr || m_last->next == nullptr);
+			TORRENT_ASSERT(rhs.m_last == nullptr || rhs.m_last->next == nullptr);
+			TORRENT_ASSERT((m_last == nullptr) == (m_first == nullptr));
+			TORRENT_ASSERT((rhs.m_last == nullptr) == (rhs.m_first == nullptr));
 
-			if (rhs.m_first == 0) return;
+			if (rhs.m_first == nullptr) return;
 
-			if (m_first == 0)
+			if (m_first == nullptr)
 			{
 				swap(rhs);
 				return;
@@ -117,22 +119,24 @@ namespace libtorrent
 
 			swap(rhs);
 			append(rhs);
+			TORRENT_ASSERT(m_last == nullptr || m_last->next == nullptr);
+			TORRENT_ASSERT(rhs.m_last == nullptr || rhs.m_last->next == nullptr);
 		}
 
 		T* pop_front()
 		{
-			TORRENT_ASSERT(m_last == 0 || m_last->next == 0);
+			TORRENT_ASSERT(m_last == nullptr || m_last->next == nullptr);
 			T* e = m_first;
 			m_first = m_first->next;
-			if (e == m_last) m_last = 0;
-			e->next = 0;
+			if (e == m_last) m_last = nullptr;
+			e->next = nullptr;
 			--m_size;
 			return e;
 		}
 		void push_front(T* e)
 		{
-			TORRENT_ASSERT(e->next == 0);
-			TORRENT_ASSERT(m_last == 0 || m_last->next == 0);
+			TORRENT_ASSERT(e->next == nullptr);
+			TORRENT_ASSERT(m_last == nullptr || m_last->next == nullptr);
 			e->next = m_first;
 			m_first = e;
 			if (!m_last) m_last = e;
@@ -140,20 +144,20 @@ namespace libtorrent
 		}
 		void push_back(T* e)
 		{
-			TORRENT_ASSERT(e->next == 0);
-			TORRENT_ASSERT(m_last == 0 || m_last->next == 0);
+			TORRENT_ASSERT(e->next == nullptr);
+			TORRENT_ASSERT(m_last == nullptr || m_last->next == nullptr);
 			if (m_last) m_last->next = e;
 			else m_first = e;
 			m_last = e;
-			e->next = 0;
+			e->next = nullptr;
 			++m_size;
 		}
 		T* get_all()
 		{
-			TORRENT_ASSERT(m_last == 0 || m_last->next == 0);
+			TORRENT_ASSERT(m_last == nullptr || m_last->next == nullptr);
 			T* e = m_first;
-			m_first = 0;
-			m_last = 0;
+			m_first = nullptr;
+			m_last = nullptr;
 			m_size = 0;
 			return e;
 		}
diff --git a/simulation/test_checking.cpp b/simulation/test_checking.cpp
index a44b853e3..b7068b3c9 100644
--- a/simulation/test_checking.cpp
+++ b/simulation/test_checking.cpp
@@ -84,7 +84,7 @@ TORRENT_TEST(cache_after_checking)
 			p.set_int(lt::settings_pack::cache_size, 100);
 		},
 		[](lt::session& ses) {
-			int cache = get_cache_size(ses);
+			int const cache = get_cache_size(ses);
 			TEST_CHECK(cache > 0);
 
 			std::vector<lt::torrent_handle> tor = ses.get_torrents();
@@ -102,7 +102,7 @@ TORRENT_TEST(checking_no_cache)
 			p.set_int(lt::settings_pack::cache_size, 0);
 		},
 		[](lt::session& ses) {
-			int cache = get_cache_size(ses);
+			int const cache = get_cache_size(ses);
 			TEST_EQUAL(cache, 0);
 
 			std::vector<lt::torrent_handle> tor = ses.get_torrents();
@@ -121,7 +121,7 @@ TORRENT_TEST(checking_limit_volatile)
 			p.set_int(lt::settings_pack::cache_size_volatile, 2);
 		},
 		[](lt::session& ses) {
-			int cache = get_cache_size(ses);
+			int const cache = get_cache_size(ses);
 			// the cache fits 300 blocks, but only allows two volatile blocks
 			TEST_EQUAL(cache, 2);
 
@@ -141,7 +141,7 @@ TORRENT_TEST(checking_volatile_limit_cache_size)
 			p.set_int(lt::settings_pack::cache_size_volatile, 300);
 		},
 		[](lt::session& ses) {
-			int cache = get_cache_size(ses);
+			int const cache = get_cache_size(ses);
 			// the cache allows 300 volatile blocks, but only fits 2 blocks
 			TEST_CHECK(cache > 0);
 			TEST_CHECK(cache <= 10);
diff --git a/src/disk_buffer_holder.cpp b/src/disk_buffer_holder.cpp
index 4716363cf..2ffdee5e3 100644
--- a/src/disk_buffer_holder.cpp
+++ b/src/disk_buffer_holder.cpp
@@ -36,7 +36,7 @@ POSSIBILITY OF SUCH DAMAGE.
 namespace libtorrent
 {
 
-	disk_buffer_holder::disk_buffer_holder(buffer_allocator_interface& alloc, char* buf)
+	disk_buffer_holder::disk_buffer_holder(buffer_allocator_interface& alloc, char* buf) noexcept
 		: m_allocator(&alloc), m_buf(buf)
 	{
 		m_ref.storage = nullptr;
@@ -44,20 +44,20 @@ namespace libtorrent
 		m_ref.block = -1;
 	}
 
-	disk_buffer_holder& disk_buffer_holder::operator=(disk_buffer_holder&& h)
+	disk_buffer_holder& disk_buffer_holder::operator=(disk_buffer_holder&& h) noexcept
 	{
 		disk_buffer_holder(std::move(h)).swap(*this);
 		return *this;
 	}
 
-	disk_buffer_holder::disk_buffer_holder(disk_buffer_holder&& h)
+	disk_buffer_holder::disk_buffer_holder(disk_buffer_holder&& h) noexcept
 		: m_allocator(h.m_allocator), m_buf(h.m_buf), m_ref(h.m_ref)
 	{
 		// we own this buffer now
 		h.release();
 	}
 
-	disk_buffer_holder::disk_buffer_holder(buffer_allocator_interface& alloc, disk_io_job const& j)
+	disk_buffer_holder::disk_buffer_holder(buffer_allocator_interface& alloc, disk_io_job const& j) noexcept
 		: m_allocator(&alloc), m_buf(j.buffer.disk_block), m_ref(j.d.io.ref)
 	{
 		TORRENT_ASSERT(m_ref.storage == nullptr || m_ref.piece >= 0);
@@ -94,7 +94,7 @@ namespace libtorrent
 		m_ref.storage = nullptr;
 	}
 
-	char* disk_buffer_holder::release()
+	char* disk_buffer_holder::release() noexcept
 	{
 		char* ret = m_buf;
 		m_buf = nullptr;
diff --git a/src/peer_connection.cpp b/src/peer_connection.cpp
index e6b3e6284..d07ad2a8a 100644
--- a/src/peer_connection.cpp
+++ b/src/peer_connection.cpp
@@ -2748,11 +2748,11 @@ namespace libtorrent
 		// if the block we got is already finished, then ignore it
 		if (picker.is_downloaded(block_finished))
 		{
-			waste_reason reason;
-			if (b->timed_out) reason = waste_reason::piece_timed_out;
-			else if (b->not_wanted) reason = waste_reason::piece_cancelled;
-			else if (b->busy) reason = waste_reason::piece_end_game;
-			else reason = waste_reason::piece_unknown;
+			waste_reason const reason
+				= (b->timed_out) ? waste_reason::piece_timed_out
+				: (b->not_wanted) ? waste_reason::piece_cancelled
+				: (b->busy) ? waste_reason::piece_end_game
+				: waste_reason::piece_unknown;
 
 			t->add_redundant_bytes(p.length, reason);