diff --git a/include/libtorrent/bandwidth_manager.hpp b/include/libtorrent/bandwidth_manager.hpp
index b34f4b993..b64e575bd 100644
--- a/include/libtorrent/bandwidth_manager.hpp
+++ b/include/libtorrent/bandwidth_manager.hpp
@@ -154,7 +154,6 @@ struct bandwidth_manager
 
 	bool is_queued(PeerConnection const* peer, boost::mutex::scoped_lock& l) const
 	{
-		TORRENT_ASSERT(l.locked());
 		for (typename queue_t::const_iterator i = m_queue.begin()
 			, end(m_queue.end()); i != end; ++i)
 		{
@@ -171,7 +170,6 @@ struct bandwidth_manager
 
 	bool is_in_history(PeerConnection const* peer, boost::mutex::scoped_lock& l) const
 	{
-		TORRENT_ASSERT(l.locked());
 		for (typename history_t::const_iterator i
 			= m_history.begin(), end(m_history.end()); i != end; ++i)
 		{
@@ -313,7 +311,6 @@ private:
 
 	void hand_out_bandwidth(boost::mutex::scoped_lock& l)
 	{
-		TORRENT_ASSERT(l.locked());
 		// if we're already handing out bandwidth, just return back
 		// to the loop further down on the callstack
 		if (m_in_hand_out_bandwidth) return;
diff --git a/src/disk_io_thread.cpp b/src/disk_io_thread.cpp
index ecb18b6de..ac76263ce 100644
--- a/src/disk_io_thread.cpp
+++ b/src/disk_io_thread.cpp
@@ -182,7 +182,6 @@ namespace libtorrent
 		disk_io_thread::cache_t& cache
 		, disk_io_job const& j, mutex_t::scoped_lock& l)
 	{
-		TORRENT_ASSERT(l.locked());
 		for (cache_t::iterator i = cache.begin()
 			, end(cache.end()); i != end; ++i)
 		{
@@ -196,7 +195,6 @@ namespace libtorrent
 	{
 		ptime now = time_now();
 
-		TORRENT_ASSERT(l.locked());
 		INVARIANT_CHECK;
 		for (;;)
 		{
@@ -213,7 +211,6 @@ namespace libtorrent
 
 	void disk_io_thread::free_piece(cached_piece_entry& p, mutex_t::scoped_lock& l)
 	{
-		TORRENT_ASSERT(l.locked());
 		int piece_size = p.storage->info()->piece_size(p.piece);
 		int blocks_in_piece = (piece_size + m_block_size - 1) / m_block_size;
 
@@ -251,7 +248,6 @@ namespace libtorrent
 
 	void disk_io_thread::flush_oldest_piece(mutex_t::scoped_lock& l)
 	{
-		TORRENT_ASSERT(l.locked());
 		INVARIANT_CHECK;
 		// first look if there are any read cache entries that can
 		// be cleared
@@ -275,7 +271,6 @@ namespace libtorrent
 	void disk_io_thread::flush(disk_io_thread::cache_t::iterator e
 		, mutex_t::scoped_lock& l)
 	{
-		TORRENT_ASSERT(l.locked());
 		INVARIANT_CHECK;
 		cached_piece_entry& p = *e;
 		int piece_size = p.storage->info()->piece_size(p.piece);
@@ -340,7 +335,6 @@ namespace libtorrent
 
 	void disk_io_thread::cache_block(disk_io_job& j, mutex_t::scoped_lock& l)
 	{
-		TORRENT_ASSERT(l.locked());
 		INVARIANT_CHECK;
 		TORRENT_ASSERT(find_cached_piece(m_pieces, j, l) == m_pieces.end());
 		cached_piece_entry p;
@@ -365,8 +359,6 @@ namespace libtorrent
 	// read or -1 if there was an error
 	int disk_io_thread::read_into_piece(cached_piece_entry& p, int start_block, mutex_t::scoped_lock& l)
 	{
-		TORRENT_ASSERT(l.locked());
-
 		int piece_size = p.storage->info()->piece_size(p.piece);
 		int blocks_in_piece = (piece_size + m_block_size - 1) / m_block_size;
 
@@ -436,8 +428,6 @@ namespace libtorrent
 		, cache_t::iterator ignore
 		, mutex_t::scoped_lock& l)
 	{
-		TORRENT_ASSERT(l.locked());
-
 		if (m_cache_size - m_cache_stats.cache_size < num_blocks)
 		{
 			// there's not enough room in the cache, clear a piece
@@ -452,8 +442,6 @@ namespace libtorrent
 	// or the number of bytes read
 	int disk_io_thread::cache_read_block(disk_io_job const& j, mutex_t::scoped_lock& l)
 	{
-		TORRENT_ASSERT(l.locked());
-
 		INVARIANT_CHECK;
 
 		int piece_size = j.storage->info()->piece_size(j.piece);
@@ -543,7 +531,6 @@ namespace libtorrent
 
 	int disk_io_thread::try_read_from_cache(disk_io_job const& j, mutex_t::scoped_lock& l)
 	{
-		TORRENT_ASSERT(l.locked());
 		TORRENT_ASSERT(j.buffer);
 
 		if (!m_use_read_cache) return -2;
@@ -707,7 +694,6 @@ namespace libtorrent
 
 	char* disk_io_thread::allocate_buffer(mutex_t::scoped_lock& l)
 	{
-		TORRENT_ASSERT(l.locked());
 #ifdef TORRENT_STATS
 		++m_allocations;
 #endif
@@ -720,7 +706,6 @@ namespace libtorrent
 
 	void disk_io_thread::free_buffer(char* buf, mutex_t::scoped_lock& l)
 	{
-		TORRENT_ASSERT(l.locked());
 #ifdef TORRENT_STATS
 		--m_allocations;
 #endif
diff --git a/src/mapped_storage.cpp b/src/mapped_storage.cpp
index bb1380d88..567a281b9 100644
--- a/src/mapped_storage.cpp
+++ b/src/mapped_storage.cpp
@@ -57,8 +57,8 @@ using boost::iostreams::mapped_file_params;
 
 namespace libtorrent
 {
-	
 	namespace fs = boost::filesystem;
+	using boost::system::error_code;
 
 	struct mapped_file_pool
 	{
@@ -78,7 +78,7 @@ namespace libtorrent
 #ifndef NDEBUG
 				if (file_size > 0)
 				{
-					fs::system_error_type ec;
+					error_code ec;
 					fs::file_status st = fs::status(path, ec);
 					TORRENT_ASSERT(!fs::exists(st));
 				}
@@ -197,7 +197,7 @@ namespace libtorrent
 			size_type start = (offset / view_size) * view_size;
 			TORRENT_ASSERT(start + view_size >= offset + length);
 
-			fs::system_error_type ec;
+			error_code ec;
 			fs::file_status st = fs::status(p, ec);
 			
 			m_files.push_back(file_entry());