diff --git a/ChangeLog b/ChangeLog
index 576fd4753..abe66b596 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,4 @@
+	* handle invalid arguments to set_piece_deadline()
 	* move_storage did not work for torrents without metadata
 	* improve shutdown time by only announcing to trackers whose IP we know
 	* fix python3 portability issue in python binding
diff --git a/include/libtorrent/torrent_handle.hpp b/include/libtorrent/torrent_handle.hpp
index de5528c79..ac8bb21fe 100644
--- a/include/libtorrent/torrent_handle.hpp
+++ b/include/libtorrent/torrent_handle.hpp
@@ -375,14 +375,14 @@ namespace libtorrent
 		// deadline (and flags) of a piece can be changed by calling this
 		// function again.
 		// 
-		// The ``flags`` parameter can be used to ask libtorrent to send an alert
+		// The ``flags`` parameter can be used to ask libtorrent to post an alert
 		// once the piece has been downloaded, by passing alert_when_available.
 		// When set, the read_piece_alert alert will be delivered, with the piece
 		// data, when it's downloaded.
 		// 
 		// If the piece is already downloaded when this call is made, nothing
 		// happens, unless the alert_when_available flag is set, in which case it
-		// will do the same thing as calling read_piece() for ``index``.
+		// will have the same effect as calling read_piece() for ``index``.
 		// 
 		// ``deadline`` is the number of milliseconds until this piece should be
 		// completed.
diff --git a/src/torrent.cpp b/src/torrent.cpp
index 58f1e1d8d..e22807bb3 100644
--- a/src/torrent.cpp
+++ b/src/torrent.cpp
@@ -5235,7 +5235,13 @@ namespace libtorrent
 	{
 		INVARIANT_CHECK;
 
-		if (m_abort)
+		TORRENT_ASSERT_PRECOND(piece >= 0);
+		TORRENT_ASSERT_PRECOND(valid_metadata());
+		TORRENT_ASSERT_PRECOND(valid_metadata() && piece < m_torrent_file->num_pieces());
+
+		if (m_abort || !valid_metadata()
+			|| piece < 0
+			|| piece >= m_torrent_file->num_pieces())
 		{
 			// failed
 			if (flags & torrent_handle::alert_when_available)