diff --git a/ChangeLog b/ChangeLog
index ed0e9227b..e15fe19d4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,6 @@
 1.2.2 release
 
+	* fix updating of is_finished torrent status, when changing piece priorities
 	* fix regression in &left= reporting when adding a seeding torrent
 	* fix integer overflow in http parser
 	* improve sanitation of symlinks, to support more complex link targets
diff --git a/include/libtorrent/piece_picker.hpp b/include/libtorrent/piece_picker.hpp
index 5bbf8634f..6574b49f5 100644
--- a/include/libtorrent/piece_picker.hpp
+++ b/include/libtorrent/piece_picker.hpp
@@ -434,8 +434,24 @@ namespace libtorrent {
 		// been flushed to disk yet)
 		int num_passed() const { return m_num_passed; }
 
-		// return true if we have all the pieces we wanted
-		bool is_finished() const { return m_num_have - m_num_have_filtered == num_pieces() - m_num_filtered; }
+		// return true if all the pieces we want have passed the hash check (but
+		// may not have been written to disk yet)
+		bool is_finished() const
+		{
+			// this expression warrants some explanation:
+			// if the number of pieces we *want* to download
+			// is less than or (more likely) equal to the number of pieces that
+			// have passed the hash check (discounting the pieces that have passed
+			// the check but then had their priority set to 0). Then we're
+			// finished. Note that any piece we *have* implies it's both passed the
+			// hash check *and* been written to disk.
+			// num_pieces() - m_num_filtered - m_num_have_filtered
+			//   <= (num_passed() - m_num_have_filtered)
+			// this can be simplified. Note how m_num_have_filtered appears on both
+			// side of the equation.
+			//
+			return num_pieces() - m_num_filtered <= num_passed();
+		}
 
 		bool is_seeding() const { return m_num_have == num_pieces(); }
 
diff --git a/simulation/setup_swarm.cpp b/simulation/setup_swarm.cpp
index 50b9643e7..bb84c46a1 100644
--- a/simulation/setup_swarm.cpp
+++ b/simulation/setup_swarm.cpp
@@ -146,6 +146,15 @@ bool is_seed(lt::session& ses)
 	return h.status().is_seeding;
 }
 
+bool is_finished(lt::session& ses)
+{
+	auto handles = ses.get_torrents();
+	TEST_EQUAL(handles.size(), 1);
+	if (handles.empty()) return false;
+	auto h = handles[0];
+	return h.status().is_finished;
+}
+
 int completed_pieces(lt::session& ses)
 {
 	auto handles = ses.get_torrents();
diff --git a/simulation/setup_swarm.hpp b/simulation/setup_swarm.hpp
index 6c83b7b9e..876d6ae07 100644
--- a/simulation/setup_swarm.hpp
+++ b/simulation/setup_swarm.hpp
@@ -78,6 +78,7 @@ void setup_swarm(int num_nodes
 
 bool has_metadata(lt::session& ses);
 bool is_seed(lt::session& ses);
+bool is_finished(lt::session& ses);
 int completed_pieces(lt::session& ses);
 void add_extra_peers(lt::session& ses);
 lt::torrent_status get_status(lt::session& ses);
diff --git a/simulation/test_transfer.cpp b/simulation/test_transfer.cpp
index a0110c13f..13cfb8f97 100644
--- a/simulation/test_transfer.cpp
+++ b/simulation/test_transfer.cpp
@@ -388,3 +388,24 @@ TORRENT_TEST(piece_extent_affinity)
 	);
 }
 
+TORRENT_TEST(is_finished)
+{
+	using namespace lt;
+	run_test(
+		[](lt::session&, lt::session&) {},
+		[](lt::session& ses, lt::alert const* a) {
+			if (alert_cast<piece_finished_alert>(a))
+			{
+				TEST_EQUAL(is_finished(ses), false);
+				std::vector<download_priority_t> prio(4, dont_download);
+				ses.get_torrents()[0].prioritize_files(prio);
+				TEST_EQUAL(is_finished(ses), true);
+			}
+		},
+		[](std::shared_ptr<lt::session> ses[2]) {
+				TEST_EQUAL(is_finished(*ses[0]), true);
+				TEST_EQUAL(is_finished(*ses[1]), true);
+		}
+	);
+}
+
diff --git a/src/torrent.cpp b/src/torrent.cpp
index 9b1ac53aa..fee99a3bb 100644
--- a/src/torrent.cpp
+++ b/src/torrent.cpp
@@ -7604,12 +7604,7 @@ bool is_downloading_state(int const st)
 	bool torrent::is_finished() const
 	{
 		if (is_seed()) return true;
-
-		// this is slightly different from m_picker->is_finished()
-		// because any piece that has *passed* is considered here,
-		// which may be more than the piece we *have* (i.e. written to disk)
-		return valid_metadata() && has_picker()
-			&& m_picker->want().num_pieces - m_picker->num_passed() == 0;
+		return valid_metadata() && has_picker() && m_picker->is_finished();
 	}
 
 	bool torrent::is_inactive() const
diff --git a/test/test_torrent.cpp b/test/test_torrent.cpp
index 30d8cdb67..a0ca5e721 100644
--- a/test/test_torrent.cpp
+++ b/test/test_torrent.cpp
@@ -203,8 +203,7 @@ TORRENT_TEST(total_wanted)
 	std::vector<char> tmp;
 	bencode(std::back_inserter(tmp), t.generate());
 	error_code ec;
-	auto info = std::make_shared<torrent_info>(
-		tmp, std::ref(ec), from_span);
+	auto info = std::make_shared<torrent_info>(tmp, std::ref(ec), from_span);
 
 	settings_pack pack = settings();
 	pack.set_int(settings_pack::alert_mask, alert::storage_notification);
@@ -220,8 +219,6 @@ TORRENT_TEST(total_wanted)
 	p.file_priorities.resize(4, 0_pri);
 	p.file_priorities[1] = 1_pri;
 
-	p.ti = info;
-
 	torrent_handle h = ses.add_torrent(std::move(p));
 
 	torrent_status st = h.status();