diff --git a/include/libtorrent/address.hpp b/include/libtorrent/address.hpp
index 02461dc2e..737152baf 100644
--- a/include/libtorrent/address.hpp
+++ b/include/libtorrent/address.hpp
@@ -35,28 +35,13 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #include "libtorrent/config.hpp"
 
-#include "libtorrent/aux_/disable_warnings_push.hpp"
-
-#ifdef __OBJC__
-#define Protocol Protocol_
-#endif
-
-#if defined TORRENT_WINDOWS || defined TORRENT_CYGWIN
-// asio assumes that the windows error codes are defined already
-#include <winsock2.h>
-#endif
-
-#include <boost/asio/ip/address.hpp>
-
 #if defined TORRENT_BUILD_SIMULATOR
 #include "simulator/simulator.hpp"
-#endif
-
+#else
+#include "libtorrent/aux_/disable_warnings_push.hpp"
+#include <boost/asio/ip/address.hpp>
 #include "libtorrent/aux_/disable_warnings_pop.hpp"
-
-#ifdef __OBJC__
-#undef Protocol
-#endif
+#endif // SIMULATOR
 
 namespace libtorrent
 {
diff --git a/include/libtorrent/alert.hpp b/include/libtorrent/alert.hpp
index 328f27a20..af7c7a6a9 100644
--- a/include/libtorrent/alert.hpp
+++ b/include/libtorrent/alert.hpp
@@ -33,7 +33,6 @@ POSSIBILITY OF SUCH DAMAGE.
 #ifndef TORRENT_ALERT_HPP_INCLUDED
 #define TORRENT_ALERT_HPP_INCLUDED
 
-#include <deque>
 #include <string>
 
 // OVERVIEW
diff --git a/include/libtorrent/announce_entry.hpp b/include/libtorrent/announce_entry.hpp
index e3a920674..f8d1caf4e 100644
--- a/include/libtorrent/announce_entry.hpp
+++ b/include/libtorrent/announce_entry.hpp
@@ -34,7 +34,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #define TORRENT_ANNOUNCE_ENTRY_HPP_INCLUDED
 
 #include "libtorrent/config.hpp"
-#include "libtorrent/time.hpp" // for time_point
+#include "libtorrent/time.hpp"
 #include "libtorrent/error_code.hpp"
 
 #include <string>
@@ -42,10 +42,6 @@ POSSIBILITY OF SUCH DAMAGE.
 
 namespace libtorrent
 {
-	namespace aux {
-		struct session_settings;
-	}
-
 	// this class holds information about one bittorrent tracker, as it
 	// relates to a specific torrent.
 	struct TORRENT_EXPORT announce_entry
@@ -161,7 +157,7 @@ namespace libtorrent
 
 		// updates the failure counter and time-outs for re-trying.
 		// This is called when the tracker announce fails.
-		void failed(aux::session_settings const& sett, int retry_interval = 0);
+		void failed(time_duration tracker_backoff, int retry_interval = 0);
 
 #ifndef TORRENT_NO_DEPRECATE
 		// deprecated in 1.0
diff --git a/include/libtorrent/aux_/proxy_settings.hpp b/include/libtorrent/aux_/proxy_settings.hpp
index 83d6479d2..add73c473 100644
--- a/include/libtorrent/aux_/proxy_settings.hpp
+++ b/include/libtorrent/aux_/proxy_settings.hpp
@@ -33,7 +33,6 @@ POSSIBILITY OF SUCH DAMAGE.
 #ifndef TORRENT_PROXY_SETTINGS_HPP_INCLUDED
 #define TORRENT_PROXY_SETTINGS_HPP_INCLUDED
 
-#include "libtorrent/version.hpp"
 #include "libtorrent/config.hpp"
 
 #include <string>
@@ -138,8 +137,6 @@ namespace aux {
 	};
 
 
-}
-}
+}}
 
 #endif
-
diff --git a/include/libtorrent/aux_/session_settings.hpp b/include/libtorrent/aux_/session_settings.hpp
index c9ba58961..74ab04b56 100644
--- a/include/libtorrent/aux_/session_settings.hpp
+++ b/include/libtorrent/aux_/session_settings.hpp
@@ -33,7 +33,6 @@ POSSIBILITY OF SUCH DAMAGE.
 #ifndef TORRENT_AUX_SESSION_SETTINGS_HPP_INCLUDED
 #define TORRENT_AUX_SESSION_SETTINGS_HPP_INCLUDED
 
-#include "libtorrent/version.hpp"
 #include "libtorrent/config.hpp"
 #include "libtorrent/settings_pack.hpp"
 #include "libtorrent/assert.hpp"
@@ -102,4 +101,3 @@ namespace libtorrent { namespace aux
 } }
 
 #endif
-
diff --git a/include/libtorrent/session_handle.hpp b/include/libtorrent/session_handle.hpp
index dfade87c6..fae283795 100644
--- a/include/libtorrent/session_handle.hpp
+++ b/include/libtorrent/session_handle.hpp
@@ -45,6 +45,10 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #include "libtorrent/kademlia/dht_storage.hpp"
 
+#ifndef TORRENT_NO_DEPRECATE
+#include <deque>
+#endif
+
 namespace libtorrent
 {
 	struct plugin;
diff --git a/include/libtorrent/settings_pack.hpp b/include/libtorrent/settings_pack.hpp
index 5a2fe27a8..c42b62959 100644
--- a/include/libtorrent/settings_pack.hpp
+++ b/include/libtorrent/settings_pack.hpp
@@ -61,7 +61,8 @@ namespace libtorrent
 
 	TORRENT_EXTRA_EXPORT boost::shared_ptr<settings_pack> load_pack_from_dict(bdecode_node const& settings);
 	TORRENT_EXTRA_EXPORT void save_settings_to_dict(aux::session_settings const& s, entry::dictionary_type& sett);
-	TORRENT_EXTRA_EXPORT void apply_pack(settings_pack const* pack, aux::session_settings& sett, aux::session_impl* ses = 0);
+	TORRENT_EXTRA_EXPORT void apply_pack(settings_pack const* pack, aux::session_settings& sett
+		, aux::session_impl* ses = nullptr);
 
 	TORRENT_EXPORT int setting_by_name(std::string const& name);
 	TORRENT_EXPORT char const* name_for_setting(int s);
diff --git a/include/libtorrent/torrent_handle.hpp b/include/libtorrent/torrent_handle.hpp
index ca6f17476..012fad0cc 100644
--- a/include/libtorrent/torrent_handle.hpp
+++ b/include/libtorrent/torrent_handle.hpp
@@ -1223,7 +1223,7 @@ namespace libtorrent
 		// directory, if there is one. The source files will still be removed in
 		// that case.
 		// 
-		// Files that have been renamed to have absolute pahts are not moved by
+		// Files that have been renamed to have absolute paths are not moved by
 		// this function. Keep in mind that files that don't belong to the
 		// torrent but are stored in the torrent's directory may be moved as
 		// well. This goes for files that have been renamed to absolute paths
diff --git a/src/announce_entry.cpp b/src/announce_entry.cpp
index d0c110253..3f3d7e8d5 100644
--- a/src/announce_entry.cpp
+++ b/src/announce_entry.cpp
@@ -41,10 +41,10 @@ namespace libtorrent
 	enum
 	{
 		// wait at least 5 seconds before retrying a failed tracker
-		tracker_retry_delay_min = 5
+		tracker_retry_delay_min = 5,
 		// when tracker_failed_max trackers
 		// has failed, wait 60 minutes instead
-		, tracker_retry_delay_max = 60 * 60
+		tracker_retry_delay_max = 60 * 60
 	};
 
 	announce_entry::announce_entry(std::string const& u)
@@ -99,14 +99,15 @@ namespace libtorrent
 		min_announce = min_time();
 	}
 
-	void announce_entry::failed(aux::session_settings const& sett, int retry_interval)
+	void announce_entry::failed(time_duration const tracker_backoff, int const retry_interval)
 	{
 		++fails;
 		// the exponential back-off ends up being:
 		// 7, 15, 27, 45, 95, 127, 165, ... seconds
 		// with the default tracker_backoff of 250
+		int const tracker_backoff_seconds = total_seconds(tracker_backoff);
 		int delay = (std::min)(tracker_retry_delay_min + int(fails) * int(fails)
-			* tracker_retry_delay_min * sett.get_int(settings_pack::tracker_backoff) / 100
+			* tracker_retry_delay_min * tracker_backoff_seconds / 100
 			, int(tracker_retry_delay_max));
 		delay = (std::max)(delay, retry_interval);
 		next_announce = aux::time_now() + seconds(delay);
diff --git a/src/create_torrent.cpp b/src/create_torrent.cpp
index 5860f7626..bb167f3dd 100644
--- a/src/create_torrent.cpp
+++ b/src/create_torrent.cpp
@@ -42,7 +42,6 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/performance_counters.hpp" // for counters
 #include "libtorrent/alert_manager.hpp"
 
-#include <boost/next_prior.hpp>
 #include <boost/shared_ptr.hpp>
 #include <boost/make_shared.hpp>
 
@@ -55,9 +54,6 @@ using namespace std::placeholders;
 
 namespace libtorrent
 {
-
-	class alert;
-
 	namespace
 	{
 		inline bool default_pred(std::string const&) { return true; }
@@ -740,6 +736,4 @@ namespace libtorrent
 		if (str == nullptr) m_created_by.clear();
 		else m_created_by = str;
 	}
-
 }
-
diff --git a/src/disk_buffer_pool.cpp b/src/disk_buffer_pool.cpp
index adf30e3ed..d042ba4fc 100644
--- a/src/disk_buffer_pool.cpp
+++ b/src/disk_buffer_pool.cpp
@@ -36,18 +36,11 @@ POSSIBILITY OF SUCH DAMAGE.
 #include "libtorrent/allocator.hpp"
 #include "libtorrent/aux_/session_settings.hpp"
 #include "libtorrent/io_service.hpp"
-#include "libtorrent/alert.hpp"
-#include "libtorrent/alert_types.hpp"
 #include "libtorrent/disk_observer.hpp"
 #include "libtorrent/platform_util.hpp" // for total_physical_ram
 
 #include "libtorrent/aux_/disable_warnings_push.hpp"
 
-#include <algorithm>
-#include <functional>
-#include <boost/system/error_code.hpp>
-#include <boost/shared_ptr.hpp>
-
 #if TORRENT_HAVE_MMAP
 #include <sys/mman.h>
 #endif
diff --git a/src/proxy_settings.cpp b/src/proxy_settings.cpp
index 807896d3c..55c04f293 100644
--- a/src/proxy_settings.cpp
+++ b/src/proxy_settings.cpp
@@ -75,4 +75,3 @@ proxy_settings::proxy_settings(aux::session_settings const& sett)
 
 } // namespace aux
 } // namespace libtorrent
-
diff --git a/src/smart_ban.cpp b/src/smart_ban.cpp
index 293c86201..0ac7e1eec 100644
--- a/src/smart_ban.cpp
+++ b/src/smart_ban.cpp
@@ -32,13 +32,6 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #ifndef TORRENT_DISABLE_EXTENSIONS
 
-#include "libtorrent/aux_/disable_warnings_push.hpp"
-
-#include <boost/shared_ptr.hpp>
-#include <boost/enable_shared_from_this.hpp>
-
-#include "libtorrent/aux_/disable_warnings_pop.hpp"
-
 #include <vector>
 #include <map>
 #include <utility>
@@ -91,10 +84,10 @@ namespace
 			// CRCs from the time it failed and ban the peers that
 			// sent bad blocks
 			std::map<piece_block, block_entry>::iterator i = m_block_hashes.lower_bound(piece_block(p, 0));
-			if (i == m_block_hashes.end() || int(i->first.piece_index) != p) return;
+			if (i == m_block_hashes.end() || i->first.piece_index != p) return;
 
 			int size = m_torrent.torrent_file().piece_size(p);
-			peer_request r = {p, 0, (std::min)(16*1024, size)};
+			peer_request r = {p, 0, (std::min)(16 * 1024, size)};
 			piece_block pb(p, 0);
 			while (size > 0)
 			{
@@ -114,9 +107,9 @@ namespace
 				if (i == m_block_hashes.end() || int(i->first.piece_index) != p)
 					break;
 
-				r.start += 16*1024;
-				size -= 16*1024;
-				r.length = (std::min)(16*1024, size);
+				r.start += 16 * 1024;
+				size -= 16 * 1024;
+				r.length = (std::min)(16 * 1024, size);
 				++pb.block_index;
 			}
 
diff --git a/src/storage.cpp b/src/storage.cpp
index d97891d65..80d28672c 100644
--- a/src/storage.cpp
+++ b/src/storage.cpp
@@ -610,7 +610,6 @@ namespace libtorrent
 	{
 		m_stat_cache.reserve(files().num_files());
 
-		std::string file_path;
 		for (int i = 0; i < files().num_files(); ++i)
 		{
 			std::int64_t sz = m_stat_cache.get_filesize(
@@ -1541,7 +1540,7 @@ namespace libtorrent
 	// check if the fastresume data is up to date
 	// if it is, use it and return true. If it
 	// isn't return false and the full check
-	// will be run. If the links pointer is non-nullptr, it has the same number
+	// will be run. If the links pointer is non-empty, it has the same number
 	// of elements as there are files. Each element is either empty or contains
 	// the absolute path to a file identical to the corresponding file in this
 	// torrent. The storage must create hard links (or copy) those files. If
diff --git a/src/torrent.cpp b/src/torrent.cpp
index 800b75332..78891bc8d 100644
--- a/src/torrent.cpp
+++ b/src/torrent.cpp
@@ -11256,7 +11256,8 @@ namespace libtorrent
 			announce_entry* ae = find_tracker(r);
 			if (ae)
 			{
-				ae->failed(settings(), retry_interval);
+				ae->failed(seconds(settings().get_int(settings_pack::tracker_backoff))
+					, retry_interval);
 				ae->last_error = ec;
 				ae->message = msg;
 				int tracker_index = ae - &m_trackers[0];
@@ -11272,7 +11273,7 @@ namespace libtorrent
 				|| r.triggered_manually)
 			{
 				m_ses.alerts().emplace_alert<tracker_error_alert>(get_handle()
-					, ae?ae->fails:0, response_code, r.url, ec, msg);
+					, ae ? ae->fails : 0, response_code, r.url, ec, msg);
 			}
 		}
 		else
diff --git a/src/torrent_info.cpp b/src/torrent_info.cpp
index 8898b9a06..0f29c3de2 100644
--- a/src/torrent_info.cpp
+++ b/src/torrent_info.cpp
@@ -80,7 +80,7 @@ namespace libtorrent
 	} // anonymous namespace
 
 	// fixes invalid UTF-8 sequences
-	TORRENT_EXTRA_EXPORT bool verify_encoding(std::string& target)
+	bool verify_encoding(std::string& target)
 	{
 		if (target.empty()) return true;
 
diff --git a/src/torrent_peer.cpp b/src/torrent_peer.cpp
index 393cd1ac0..7881ee164 100644
--- a/src/torrent_peer.cpp
+++ b/src/torrent_peer.cpp
@@ -107,13 +107,13 @@ namespace libtorrent
 			if (e1 > e2) swap(e1, e2);
 			address_v6::bytes_type b1 = e1.address().to_v6().to_bytes();
 			address_v6::bytes_type b2 = e2.address().to_v6().to_bytes();
-			int mask = memcmp(&b1[0], &b2[0], 4) ? 0
-				: memcmp(&b1[0], &b2[0], 6) ? 1 : 2;
-			apply_mask(&b1[0], v6mask[mask], 8);
-			apply_mask(&b2[0], v6mask[mask], 8);
+			int const mask = std::memcmp(b1.data(), b2.data(), 4) ? 0
+				: std::memcmp(b1.data(), b2.data(), 6) ? 1 : 2;
+			apply_mask(b1.data(), v6mask[mask], 8);
+			apply_mask(b2.data(), v6mask[mask], 8);
 			std::uint64_t addrbuf[4];
-			memcpy(&addrbuf[0], &b1[0], 16);
-			memcpy(&addrbuf[2], &b2[0], 16);
+			memcpy(&addrbuf[0], b1.data(), 16);
+			memcpy(&addrbuf[2], b2.data(), 16);
 			ret = crc32c(addrbuf, 4);
 		}
 #endif
@@ -313,4 +313,3 @@ namespace libtorrent
 	}
 
 }
-
diff --git a/src/ut_metadata.cpp b/src/ut_metadata.cpp
index f649d4387..752b590f9 100644
--- a/src/ut_metadata.cpp
+++ b/src/ut_metadata.cpp
@@ -32,18 +32,12 @@ POSSIBILITY OF SUCH DAMAGE.
 
 #ifndef TORRENT_DISABLE_EXTENSIONS
 
-#include "libtorrent/aux_/disable_warnings_push.hpp"
-
-#include <boost/shared_ptr.hpp>
 #include <functional>
-
 #include <vector>
 #include <utility>
 #include <numeric>
 #include <cstdio>
 
-#include "libtorrent/aux_/disable_warnings_pop.hpp"
-
 #include "libtorrent/peer_connection.hpp"
 #include "libtorrent/bt_peer_connection.hpp"
 #include "libtorrent/peer_connection_handle.hpp"
diff --git a/test/test_primitives.cpp b/test/test_primitives.cpp
index 2294ce07a..13ab9bd22 100644
--- a/test/test_primitives.cpp
+++ b/test/test_primitives.cpp
@@ -71,11 +71,10 @@ TORRENT_TEST(primitives)
 	// on failing announces
 	announce_entry ae("dummy");
 	int last = 0;
-	aux::session_settings sett;
-	sett.set_int(settings_pack::tracker_backoff, 250);
+	auto const tracker_backoff = seconds(250);
 	for (int i = 0; i < 10; ++i)
 	{
-		ae.failed(sett, 5);
+		ae.failed(tracker_backoff, 5);
 		int delay = ae.next_announce_in();
 		TEST_CHECK(delay > last);
 		last = delay;