connection.go | 2 ++
 global.go     | 2 ++

diff --git a/connection.go b/connection.go
index 28152d5a60c13630423f84dcd94ef1cd523d5706..6d11f8ab1334e09e9574b9e9c3830a344e8208dd 100644
--- a/connection.go
+++ b/connection.go
@@ -1326,6 +1326,8 @@
 	err := func() error {
 		cl.unlock()
 		defer cl.lock()
+		concurrentChunkWrites.Add(1)
+		defer concurrentChunkWrites.Add(-1)
 		// Write the chunk out. Note that the upper bound on chunk writing
 		// concurrency will be the number of connections. We write inline with
 		// receiving the chunk (with this lock dance), because we want to
diff --git a/global.go b/global.go
index b66dd9dd816dd76cd27ceb522894190f1694da71..b9950cb2ef6d23b35ba627d40d9f1e0c12736365 100644
--- a/global.go
+++ b/global.go
@@ -49,4 +49,6 @@ 	// Track the effectiveness of Torrent.connPieceInclinationPool.
 	pieceInclinationsReused = expvar.NewInt("pieceInclinationsReused")
 	pieceInclinationsNew    = expvar.NewInt("pieceInclinationsNew")
 	pieceInclinationsPut    = expvar.NewInt("pieceInclinationsPut")
+
+	concurrentChunkWrites = expvar.NewInt("torrentConcurrentChunkWrites")
 )