diff --git a/docs/manual.rst b/docs/manual.rst
index 6741a672a..61005ad7c 100644
--- a/docs/manual.rst
+++ b/docs/manual.rst
@@ -356,9 +356,9 @@ add_torrent()
 
 	::
 
-		typedef storage_interface* (&storage_constructor_type)(
-			file_storage const&, file_storage const*, fs::path const&, file_pool&
-			, std::vector<boost::uint8_t> const&);
+		typedef boost::function<storage_interface*(file_storage const&
+			, file_storage const*, std::string const&, file_pool&
+			, std::vector<boost::uint8_t> const&) storage_constructor_type;
 
 		struct add_torrent_params
 		{
@@ -382,6 +382,7 @@ add_torrent()
 			bool upload_mode;
 			std::vector<boost::uint8_t> const* file_priorities;
 			bool share_mode;
+			std::string trackerid;
 		};
 
 		torrent_handle add_torrent(add_torrent_params const& params);
@@ -514,6 +515,10 @@ a torrent. The semantics are the same as for ``torrent_handle::prioritize_files(
 ``version`` is filled in by the constructor and should be left untouched. It
 is used for forward binary compatibility.
 
+``trackerid`` is the default tracker id to be used when announcing to trackers. By default
+this is empty, and no tracker ID is used, since this is an optional argument. If
+a tracker returns a tracker ID, that ID is used instead of this.
+
 remove_torrent()
 ----------------
 
diff --git a/include/libtorrent/storage_defs.hpp b/include/libtorrent/storage_defs.hpp
index 4d674a9cc..e6d3098f4 100644
--- a/include/libtorrent/storage_defs.hpp
+++ b/include/libtorrent/storage_defs.hpp
@@ -34,6 +34,7 @@ POSSIBILITY OF SUCH DAMAGE.
 #define TORRENT_STORAGE_DEFS_HPP_INCLUDE
 
 #include "libtorrent/config.hpp"
+#include <boost/function.hpp>
 #include <string>
 
 namespace libtorrent
@@ -49,14 +50,16 @@ namespace libtorrent
 		storage_mode_compact
 	};
 	
-	typedef storage_interface* (*storage_constructor_type)(
-		file_storage const&, file_storage const*, std::string const&, file_pool&, std::vector<boost::uint8_t> const&);
+	typedef boost::function<storage_interface*(file_storage const&, file_storage const*
+		, std::string const&, file_pool&, std::vector<boost::uint8_t> const&)> storage_constructor_type;
 
 	TORRENT_EXPORT storage_interface* default_storage_constructor(
-		file_storage const&, file_storage const* mapped, std::string const&, file_pool&, std::vector<boost::uint8_t> const&);
+		file_storage const&, file_storage const* mapped, std::string const&, file_pool&
+		, std::vector<boost::uint8_t> const&);
 
 	TORRENT_EXPORT storage_interface* disabled_storage_constructor(
-		file_storage const&, file_storage const* mapped, std::string const&, file_pool&, std::vector<boost::uint8_t> const&);
+		file_storage const&, file_storage const* mapped, std::string const&, file_pool&
+		, std::vector<boost::uint8_t> const&);
 
 }