diff --git a/setup/mscs/msc2946/msc2946.go b/setup/mscs/msc2946/msc2946.go
index a2d801e4..accdbd39 100644
--- a/setup/mscs/msc2946/msc2946.go
+++ b/setup/mscs/msc2946/msc2946.go
@@ -333,7 +333,12 @@ func (w *walker) references(roomID string) (eventLookup, error) {
 	}
 	el := make(eventLookup)
 	for _, ev := range events {
-		el.set(ev)
+		// only return events that have a `via` key as per MSC1772
+		// else we'll incorrectly walk redacted events (as the link
+		// is in the state_key)
+		if gjson.GetBytes(ev.Content(), "via").Exists() {
+			el.set(ev)
+		}
 	}
 	return el, nil
 }
diff --git a/setup/mscs/msc2946/msc2946_test.go b/setup/mscs/msc2946/msc2946_test.go
index 017319dc..a7650f0b 100644
--- a/setup/mscs/msc2946/msc2946_test.go
+++ b/setup/mscs/msc2946/msc2946_test.go
@@ -254,7 +254,26 @@ func TestMSC2946(t *testing.T) {
 		if len(res.Rooms) != len(allRooms) {
 			t.Errorf("got %d rooms, want %d", len(res.Rooms), len(allRooms))
 		}
+	})
+	t.Run("can update the graph", func(t *testing.T) {
+		// remove R3 from the graph
+		rmS1ToR3 := mustCreateEvent(t, fledglingEvent{
+			RoomID:   subSpaceS1,
+			Sender:   alice,
+			Type:     msc2946.ConstSpaceChildEventType,
+			StateKey: &room3,
+			Content:  map[string]interface{}{}, // redacted
+		})
+		nopRsAPI.events[rmS1ToR3.EventID()] = rmS1ToR3
+		hooks.Run(hooks.KindNewEventPersisted, rmS1ToR3)
 
+		res := postSpaces(t, 200, "alice", rootSpace, newReq(t, map[string]interface{}{}))
+		if len(res.Events) != 6 { // one less since we don't return redacted events
+			t.Errorf("got %d events, want 6", len(res.Events))
+		}
+		if len(res.Rooms) != (len(allRooms) - 1) { // one less due to lack of R3
+			t.Errorf("got %d rooms, want %d", len(res.Rooms), len(allRooms)-1)
+		}
 	})
 }
 
diff --git a/setup/mscs/msc2946/storage.go b/setup/mscs/msc2946/storage.go
index eb4a5efb..5798310a 100644
--- a/setup/mscs/msc2946/storage.go
+++ b/setup/mscs/msc2946/storage.go
@@ -81,7 +81,7 @@ func newPostgresDatabase(dbOpts *config.DatabaseOptions) (Database, error) {
 	if d.insertEdgeStmt, err = d.db.Prepare(`
 		INSERT INTO msc2946_edges(room_version, source_room_id, dest_room_id, rel_type, event_json)
 		VALUES($1, $2, $3, $4, $5)
-		ON CONFLICT DO NOTHING
+		ON CONFLICT ON CONSTRAINT msc2946_edges_uniq DO UPDATE SET event_json = $5
 	`); err != nil {
 		return nil, err
 	}
@@ -121,7 +121,7 @@ func newSQLiteDatabase(dbOpts *config.DatabaseOptions) (Database, error) {
 	if d.insertEdgeStmt, err = d.db.Prepare(`
 		INSERT INTO msc2946_edges(room_version, source_room_id, dest_room_id, rel_type, event_json)
 		VALUES($1, $2, $3, $4, $5)
-		ON CONFLICT DO NOTHING
+		ON CONFLICT (source_room_id, dest_room_id, rel_type) DO UPDATE SET event_json = $5
 	`); err != nil {
 		return nil, err
 	}