diff --git a/docs/manual.html b/docs/manual.html
index f49e96389..b1efbbc20 100755
--- a/docs/manual.html
+++ b/docs/manual.html
@@ -103,33 +103,34 @@
 <li><a class="reference" href="#invalid-request-alert" id="id83" name="id83">invalid_request_alert</a></li>
 <li><a class="reference" href="#torrent-finished-alert" id="id84" name="id84">torrent_finished_alert</a></li>
 <li><a class="reference" href="#metadata-received-alert" id="id85" name="id85">metadata_received_alert</a></li>
-<li><a class="reference" href="#dispatcher" id="id86" name="id86">dispatcher</a></li>
+<li><a class="reference" href="#fastresume-rejected-alert" id="id86" name="id86">fastresume_rejected_alert</a></li>
+<li><a class="reference" href="#dispatcher" id="id87" name="id87">dispatcher</a></li>
 </ul>
 </li>
-<li><a class="reference" href="#exceptions" id="id87" name="id87">exceptions</a><ul>
-<li><a class="reference" href="#invalid-handle" id="id88" name="id88">invalid_handle</a></li>
-<li><a class="reference" href="#duplicate-torrent" id="id89" name="id89">duplicate_torrent</a></li>
-<li><a class="reference" href="#invalid-encoding" id="id90" name="id90">invalid_encoding</a></li>
-<li><a class="reference" href="#type-error" id="id91" name="id91">type_error</a></li>
-<li><a class="reference" href="#invalid-torrent-file" id="id92" name="id92">invalid_torrent_file</a></li>
+<li><a class="reference" href="#exceptions" id="id88" name="id88">exceptions</a><ul>
+<li><a class="reference" href="#invalid-handle" id="id89" name="id89">invalid_handle</a></li>
+<li><a class="reference" href="#duplicate-torrent" id="id90" name="id90">duplicate_torrent</a></li>
+<li><a class="reference" href="#invalid-encoding" id="id91" name="id91">invalid_encoding</a></li>
+<li><a class="reference" href="#type-error" id="id92" name="id92">type_error</a></li>
+<li><a class="reference" href="#invalid-torrent-file" id="id93" name="id93">invalid_torrent_file</a></li>
 </ul>
 </li>
-<li><a class="reference" href="#examples" id="id93" name="id93">examples</a><ul>
-<li><a class="reference" href="#dump-torrent" id="id94" name="id94">dump_torrent</a></li>
-<li><a class="reference" href="#simple-client" id="id95" name="id95">simple client</a></li>
+<li><a class="reference" href="#examples" id="id94" name="id94">examples</a><ul>
+<li><a class="reference" href="#dump-torrent" id="id95" name="id95">dump_torrent</a></li>
+<li><a class="reference" href="#simple-client" id="id96" name="id96">simple client</a></li>
 </ul>
 </li>
-<li><a class="reference" href="#fast-resume" id="id96" name="id96">fast resume</a><ul>
-<li><a class="reference" href="#file-format" id="id97" name="id97">file format</a></li>
+<li><a class="reference" href="#fast-resume" id="id97" name="id97">fast resume</a><ul>
+<li><a class="reference" href="#file-format" id="id98" name="id98">file format</a></li>
 </ul>
 </li>
-<li><a class="reference" href="#extensions" id="id98" name="id98">extensions</a><ul>
-<li><a class="reference" href="#chat-messages" id="id99" name="id99">chat messages</a></li>
-<li><a class="reference" href="#metadata-from-peers" id="id100" name="id100">metadata from peers</a></li>
+<li><a class="reference" href="#extensions" id="id99" name="id99">extensions</a><ul>
+<li><a class="reference" href="#chat-messages" id="id100" name="id100">chat messages</a></li>
+<li><a class="reference" href="#metadata-from-peers" id="id101" name="id101">metadata from peers</a></li>
 </ul>
 </li>
-<li><a class="reference" href="#filename-checks" id="id101" name="id101">filename checks</a></li>
-<li><a class="reference" href="#acknowledgements" id="id102" name="id102">acknowledgements</a></li>
+<li><a class="reference" href="#filename-checks" id="id102" name="id102">filename checks</a></li>
+<li><a class="reference" href="#acknowledgements" id="id103" name="id103">acknowledgements</a></li>
 </ul>
 </div>
 <div class="section" id="introduction">
@@ -886,9 +887,6 @@ struct torrent_handle
         bool is_piece_filtered(int index) const;
         std::vector&lt;bool&gt; filtered_pieces() const;
 
-        int num_complete() const;
-        int num_incomplete() const;
-
         bool has_metadata() const;
 
         boost::filsystem::path save_path() const;
@@ -1980,6 +1978,23 @@ struct metadata_received_alert: alert
         torrent_handle handle;
 };
 </pre>
+</div>
+<div class="section" id="fastresume-rejected-alert">
+<h2><a name="fastresume-rejected-alert">fastresume_rejected_alert</a></h2>
+<p>This alert is generated when a fastresume file has been passed to <tt class="docutils literal"><span class="pre">add_torrent</span></tt> but the
+files on disk did not match the fastresume file. The string explaints the reason why the
+resume file was rejected. It is generated at severity level <tt class="docutils literal"><span class="pre">warning</span></tt>.</p>
+<pre class="literal-block">
+struct fastresume_rejected_alert: alert
+{
+        fastresume_rejected_alert(torrent_handle const&amp; h
+                , std::string const&amp; msg);
+
+        virtual std::auto_ptr&lt;alert&gt; clone() const;
+
+        torrent_handle handle;
+};
+</pre>
 <!-- chat_message_alert
 - - - - - - - - - - - - - - - - - -
 
diff --git a/docs/manual.rst b/docs/manual.rst
index 00bef9704..ad14ac68d 100755
--- a/docs/manual.rst
+++ b/docs/manual.rst
@@ -816,9 +816,6 @@ Its declaration looks like this::
 		bool is_piece_filtered(int index) const;
 		std::vector<bool> filtered_pieces() const;
 
-		int num_complete() const;
-		int num_incomplete() const;
-
 		bool has_metadata() const;
 
 		boost::filsystem::path save_path() const;
@@ -2014,6 +2011,26 @@ It is generated at severity level ``info``.
 	};
 
 
+fastresume_rejected_alert
+-------------------------
+
+This alert is generated when a fastresume file has been passed to ``add_torrent`` but the
+files on disk did not match the fastresume file. The string explaints the reason why the
+resume file was rejected. It is generated at severity level ``warning``.
+
+::
+
+	struct fastresume_rejected_alert: alert
+	{
+		fastresume_rejected_alert(torrent_handle const& h
+			, std::string const& msg);
+
+		virtual std::auto_ptr<alert> clone() const;
+
+		torrent_handle handle;
+	};
+
+
 
 .. chat_message_alert
 	------------------
diff --git a/examples/client_test.cpp b/examples/client_test.cpp
index ae06de735..249ae25b1 100755
--- a/examples/client_test.cpp
+++ b/examples/client_test.cpp
@@ -523,8 +523,7 @@ int main(int argc, char* argv[])
 				{
 					i->get_download_queue(queue);
 					for (std::vector<partial_piece_info>::iterator i = queue.begin();
-						i != queue.end();
-						++i)
+						i != queue.end(); ++i)
 					{
 						out.width(4);
 						out.fill(' ');
diff --git a/include/libtorrent/alert_types.hpp b/include/libtorrent/alert_types.hpp
index 94bc4cba0..ef5ba1e04 100755
--- a/include/libtorrent/alert_types.hpp
+++ b/include/libtorrent/alert_types.hpp
@@ -232,6 +232,21 @@ namespace libtorrent
 		virtual std::auto_ptr<alert> clone() const
 		{ return std::auto_ptr<alert>(new listen_failed_alert(*this)); }
 	};
+
+	struct fastresume_rejected_alert: alert
+	{
+		fastresume_rejected_alert(torrent_handle const& h
+			, std::string const& msg)
+			: alert(alert::warning, msg)
+			, handle(h)
+			{}
+
+		virtual std::auto_ptr<alert> clone() const
+		{ return std::auto_ptr<alert>(new fastresume_rejected_alert(*this)); }
+
+		torrent_handle handle;
+	};
+
 }
 
 
diff --git a/include/libtorrent/session.hpp b/include/libtorrent/session.hpp
index 8370d7ad8..6b7d1c107 100755
--- a/include/libtorrent/session.hpp
+++ b/include/libtorrent/session.hpp
@@ -115,7 +115,8 @@ namespace libtorrent
 
 			void parse_resume_data(
 				const entry& rd
-				, const torrent_info& info);
+				, const torrent_info& info
+				, std::string& error);
 
 			std::vector<int> piece_map;
 			std::vector<piece_picker::downloading_piece> unfinished_pieces;
diff --git a/include/libtorrent/storage.hpp b/include/libtorrent/storage.hpp
index 5b6f9e2a6..a46ed1a25 100755
--- a/include/libtorrent/storage.hpp
+++ b/include/libtorrent/storage.hpp
@@ -68,7 +68,8 @@ namespace libtorrent
 	bool match_filesizes(
 		torrent_info const& t
 		, boost::filesystem::path p
-		, std::vector<std::pair<size_type, std::time_t> > const& sizes);
+		, std::vector<std::pair<size_type, std::time_t> > const& sizes
+		, std::string* error = 0);
 
 	struct file_allocation_failed: std::exception
 	{
diff --git a/src/session.cpp b/src/session.cpp
index 0e83e681c..2e46f7a2c 100755
--- a/src/session.cpp
+++ b/src/session.cpp
@@ -127,7 +127,8 @@ namespace libtorrent { namespace detail
 			try
 			{
 				assert(t != 0);
-				t->parse_resume_data(t->resume_data, t->torrent_ptr->torrent_file());
+				std::string error_msg;
+				t->parse_resume_data(t->resume_data, t->torrent_ptr->torrent_file(), error_msg);
 
 				// clear the resume data now that it has been used
 				// (the fast resume data is now parsed and stored in t)
@@ -142,6 +143,15 @@ namespace libtorrent { namespace detail
 					continue;
 				}
 				boost::mutex::scoped_lock l2(m_ses.m_mutex);
+
+				if (!error_msg.empty() && m_ses.m_alerts.should_post(alert::warning))
+				{
+					m_ses.m_alerts.post_alert(fastresume_rejected_alert(
+						t->torrent_ptr->get_handle()
+						, error_msg));
+					
+				}
+				
 				m_ses.m_torrents.insert(std::make_pair(t->info_hash, t->torrent_ptr));
 				if (t->torrent_ptr->is_seed() && m_ses.m_alerts.should_post(alert::info))
 				{
@@ -1188,7 +1198,8 @@ namespace libtorrent
 
 	void detail::piece_checker_data::parse_resume_data(
 		const entry& resume_data
-		, const torrent_info& info)
+		, const torrent_info& info
+		, std::string& error)
 	{
 		// if we don't have any resume data, return
 		if (resume_data.type() == entry::undefined_t) return;
@@ -1198,16 +1209,26 @@ namespace libtorrent
 		try
 		{
 			if (rd["file-format"].string() != "libtorrent resume file")
+			{
+				error = "missing file format tag";
 				return;
+			}
 
-			if (rd["file-version"].integer() != 1)
+			if (rd["file-version"].integer() > 1)
+			{
+				error = "incompatible file version "
+					+ boost::lexical_cast<std::string>(rd["file-version"].integer());
 				return;
+			}
 
 			// verify info_hash
 			const std::string &hash = rd["info-hash"].string();
 			std::string real_hash((char*)info.info_hash().begin(), (char*)info.info_hash().end());
 			if (hash != real_hash)
+			{
+				error = "mismatching info-hash: " + hash;
 				return;
+			}
 
 			// the peers
 
@@ -1218,8 +1239,7 @@ namespace libtorrent
 				std::vector<address> tmp_peers;
 				tmp_peers.reserve(peer_list.size());
 				for (entry::list_type::iterator i = peer_list.begin();
-					i != peer_list.end();
-					++i)
+					i != peer_list.end(); ++i)
 				{
 					address a(
 						(*i)["ip"].string().c_str()
@@ -1233,24 +1253,32 @@ namespace libtorrent
 			// read piece map
 			const entry::list_type& slots = rd["slots"].list();
 			if ((int)slots.size() > info.num_pieces())
+			{
+				error = "file has more slots than torrent (" + boost::lexical_cast<std::string>(slots.size()) + ")";
 				return;
+			}
 
 			std::vector<int> tmp_pieces;
 			tmp_pieces.reserve(slots.size());
 			for (entry::list_type::const_iterator i = slots.begin();
-				i != slots.end();
-				++i)
+				i != slots.end(); ++i)
 			{
 				int index = (int)i->integer();
 				if (index >= info.num_pieces() || index < -2)
+				{
+					error = "too high index number in slot map (" + boost::lexical_cast<std::string>(index) + ")";
 					return;
+				}
 				tmp_pieces.push_back(index);
 			}
 
 
 			int num_blocks_per_piece = (int)rd["blocks per piece"].integer();
 			if (num_blocks_per_piece != info.piece_length() / torrent_ptr->block_size())
+			{
+				error = "invalid number of blocks per piece (" + boost::lexical_cast<std::string>(num_blocks_per_piece) + ")";
 				return;
+			}
 
 			// the unfinished pieces
 
@@ -1259,19 +1287,25 @@ namespace libtorrent
 			std::vector<piece_picker::downloading_piece> tmp_unfinished;
 			tmp_unfinished.reserve(unfinished.size());
 			for (entry::list_type::iterator i = unfinished.begin();
-				i != unfinished.end();
-				++i)
+				i != unfinished.end(); ++i)
 			{
 				piece_picker::downloading_piece p;
 
 				p.index = (int)(*i)["piece"].integer();
 				if (p.index < 0 || p.index >= info.num_pieces())
+				{
+					error = "invalid piece index in unfinished piece list (" + boost::lexical_cast<std::string>(p.index) + ")";
 					return;
+				}
 
 				const std::string& bitmask = (*i)["bitmask"].string();
 
 				const int num_bitmask_bytes = std::max(num_blocks_per_piece / 8, 1);
-				if ((int)bitmask.size() != num_bitmask_bytes) return;
+				if ((int)bitmask.size() != num_bitmask_bytes)
+				{
+					error = "invalid size of bitmask (" + boost::lexical_cast<std::string>(bitmask.size()) + ")";
+					return;
+				}
 				for (int j = 0; j < num_bitmask_bytes; ++j)
 				{
 					unsigned char bits = bitmask[j];
@@ -1291,6 +1325,8 @@ namespace libtorrent
 				{
 					// this piece is marked as unfinished
 					// but doesn't have any storage
+					error = "piece " + boost::lexical_cast<std::string>(p.index) + " is "
+						"marked as unfinished, but doesn't have any storage";
 					return;
 				}
 
@@ -1306,7 +1342,10 @@ namespace libtorrent
 
 				// crc's didn't match, don't use the resume data
 				if (ad.integer() != adler)
+				{
+					error = "checksum mismatch on piece " + boost::lexical_cast<std::string>(p.index);
 					return;
+				}
 
 				tmp_unfinished.push_back(p);
 			}
@@ -1329,7 +1368,11 @@ namespace libtorrent
 				, boost::bind(std::less<int>(), _1, 0)) == tmp_pieces.end())
 			{
 				if (info.num_files() != (int)file_sizes.size())
+				{
+					error = "the number of files does not match the torrent ("
+						+ boost::lexical_cast<std::string>(file_sizes.size()) + ")";
 					return;
+				}
 
 				std::vector<std::pair<size_type, std::time_t> >::iterator
 					fs = file_sizes.begin();
@@ -1338,12 +1381,17 @@ namespace libtorrent
 				for (torrent_info::file_iterator i = info.begin_files()
 					, end(info.end_files()); i != end; ++i, ++fs)
 				{
-					if (i->size != fs->first) return;
+					if (i->size != fs->first)
+					{
+						error = "file size for '" + i->path.native_file_string() + "' was expected to be "
+							+ boost::lexical_cast<std::string>(i->size) + " bytes";
+						return;
+					}
 				}
 			}
 
 
-			if (!match_filesizes(info, save_path, file_sizes))
+			if (!match_filesizes(info, save_path, file_sizes, &error))
 				return;
 
 			piece_map.swap(tmp_pieces);
diff --git a/src/storage.cpp b/src/storage.cpp
index 9231f7688..cfeebf1c1 100755
--- a/src/storage.cpp
+++ b/src/storage.cpp
@@ -185,16 +185,20 @@ namespace libtorrent
 	bool match_filesizes(
 		torrent_info const& t
 		, path p
-		, std::vector<std::pair<size_type, std::time_t> > const& sizes)
+		, std::vector<std::pair<size_type, std::time_t> > const& sizes
+		, std::string* error)
 	{
-		if ((int)sizes.size() != t.num_files()) return false;
+		if ((int)sizes.size() != t.num_files())
+		{
+			if (error) *error = "mismatching number of files";
+			return false;
+		}
 		p = complete(p);
 
 		std::vector<std::pair<size_type, std::time_t> >::const_iterator s
 			= sizes.begin();
 		for (torrent_info::file_iterator i = t.begin_files();
-			i != t.end_files();
-			++i, ++s)
+			i != t.end_files(); ++i, ++s)
 		{
 			size_type size = 0;
 			std::time_t time = 0;
@@ -205,8 +209,22 @@ namespace libtorrent
 				time = last_write_time(f);
 			}
 			catch (std::exception&) {}
-			if (size != s->first || time != s->second)
+			if (size != s->first)
+			{
+				if (error) *error = "filesize mismatch for file '"
+					+ i->path.native_file_string()
+					+ "', expected to be " + boost::lexical_cast<std::string>(s->first)
+					+ " bytes";
 				return false;
+			}
+			if (time != s->second)
+			{
+				if (error) *error = "timestamp mismatch for file '"
+					+ i->path.native_file_string()
+					+ "', expected to have modification date "
+					+ boost::lexical_cast<std::string>(s->second);
+				return false;
+			}
 		}
 		return true;
 	}