diff --git a/Jamfile b/Jamfile
index 992d4349b..c6a97300f 100755
--- a/Jamfile
+++ b/Jamfile
@@ -325,6 +325,9 @@ feature iconv : auto on off : composite propagated ;
 feature.compose <iconv>on : <define>TORRENT_USE_ICONV=1 ;
 feature.compose <iconv>off : <define>TORRENT_USE_ICONV=0 ;
 
+feature valgrind : off on : composite propagated link-incompatible ;
+feature.compose <valgrind>on : <define>TORRENT_USE_VALGRIND=1 ;
+
 feature full-stats : on off : composite propagated link-incompatible ;
 feature.compose <full-stats>off : <define>TORRENT_DISABLE_FULL_STATS ;
 
diff --git a/src/piece_picker.cpp b/src/piece_picker.cpp
index 2d5caaa8d..42a544bf8 100644
--- a/src/piece_picker.cpp
+++ b/src/piece_picker.cpp
@@ -185,20 +185,33 @@ namespace libtorrent
 		std::vector<downloading_piece>::iterator i = std::lower_bound(m_downloads.begin()
 			, m_downloads.end(), cmp);
 		TORRENT_ASSERT(i == m_downloads.end() || i->index != piece);
-		i = m_downloads.insert(i, downloading_piece());
-		downloading_piece& ret = *i;
+		downloading_piece ret;
 		ret.index = piece;
 		ret.info = &m_block_info[block_index];
+#ifdef TORRENT_USE_VALGRIND
+		VALGRIND_CHECK_VALUE_IS_DEFINED(piece);
+		VALGRIND_CHECK_VALUE_IS_DEFINED(block_index);
+#endif
 		for (int i = 0; i < m_blocks_per_piece; ++i)
 		{
 			ret.info[i].num_peers = 0;
 			ret.info[i].state = block_info::state_none;
 			ret.info[i].peer = 0;
+#ifdef TORRENT_USE_VALGRIND
+			VALGRIND_CHECK_VALUE_IS_DEFINED(ret.info[i].num_peers);
+			VALGRIND_CHECK_VALUE_IS_DEFINED(ret.info[i].state);
+			VALGRIND_CHECK_VALUE_IS_DEFINED(ret.info[i].peer);
+#endif
 #if defined TORRENT_DEBUG || TORRENT_RELEASE_ASSERTS
 			ret.info[i].piece_index = piece;
 #endif
 		}
-		return ret;
+
+#ifdef TORRENT_USE_VALGRIND
+		VALGRIND_CHECK_VALUE_IS_DEFINED(ret);
+#endif
+		i = m_downloads.insert(i, ret);
+		return *i;
 	}
 
 	void piece_picker::erase_download_piece(std::vector<downloading_piece>::iterator i)
diff --git a/src/session_impl.cpp b/src/session_impl.cpp
index 256511438..562bf467c 100644
--- a/src/session_impl.cpp
+++ b/src/session_impl.cpp
@@ -46,6 +46,10 @@ POSSIBILITY OF SUCH DAMAGE.
 #include <boost/bind.hpp>
 #include <boost/function_equal.hpp>
 
+#ifdef TORRENT_USE_VALGRIND
+#include <valgrind/memcheck.h>
+#endif
+
 #ifdef _MSC_VER
 #pragma warning(pop)
 #endif
@@ -3919,7 +3923,11 @@ retry:
 
 			int total_job_time = cs.cumulative_job_time == 0 ? 1 : cs.cumulative_job_time;
 
+#ifdef TORRENT_USE_VALGRIND
+#define STAT_LOG(type, val) VALGRIND_CHECK_VALUE_IS_DEFINED(val); fprintf(m_stats_logger, "%" #type "\t", val)
+#else
 #define STAT_LOG(type, val) fprintf(m_stats_logger, "%" #type "\t", val)
+#endif
 
 			STAT_LOG(f, total_milliseconds(now - m_last_log_rotation) / 1000.f);
 			size_type uploaded = m_stat.total_upload() - m_last_uploaded;
diff --git a/test/Jamfile b/test/Jamfile
index 50953ff40..d3cc95261 100644
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -96,7 +96,7 @@ project
    ;
 
 feature launcher : none valgrind : composite ;
-feature.compose <launcher>valgrind : <testing.launcher>"valgrind --tool=memcheck -v --track-origins=yes --error-exitcode=1" ;
+feature.compose <launcher>valgrind : <testing.launcher>"valgrind --tool=memcheck -v --num-callers=20 --read-var-info=yes --track-origins=yes --error-exitcode=1" <valgrind>on ;
 
 test-suite libtorrent : 	
 	[ run test_file_storage.cpp ]
diff --git a/tools/parse_test_results.py b/tools/parse_test_results.py
index e5f608f4b..df6a07008 100755
--- a/tools/parse_test_results.py
+++ b/tools/parse_test_results.py
@@ -55,9 +55,11 @@ def style_output(o):
 			' : error LNK' in l or ': undefined reference to ' in l or \
 			'jump or move depends on uninitialised value(s)' in l or \
 			'Invalid read of size' in l or \
-			'Invalid write of size' in l:
+			'Invalid write of size' in l or \
+			'Use of uninitialised value of size' in l:
 			ret += '<span class="compile-error">%s</span>\n' % l
-		elif ': warning: ' in l or ') : warning C' in l:
+		elif ': warning: ' in l or ') : warning C' in l \
+			or 'Uninitialised value was created by a' in l:
 			ret += '<span class="compile-warning">%s</span>\n' % l
 		elif l == '====== END OUTPUT ======' and not subtle:
 			ret += '<span class="subtle">%s\n' % l