From dd7c0cca6c749a2177212e9a7b3dd4eca5e5dd74 Mon Sep 17 00:00:00 2001
From: nick_m <mainsbridge@gmail.com>
Date: Sun, 4 Sep 2016 04:19:34 +1000
Subject: [PATCH] Sanity check for TempoMap::get_grid ()

---
 libs/ardour/tempo.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libs/ardour/tempo.cc b/libs/ardour/tempo.cc
index 4257767458..41a8f91ec5 100644
--- a/libs/ardour/tempo.cc
+++ b/libs/ardour/tempo.cc
@@ -3474,7 +3474,7 @@ TempoMap::get_grid (vector<TempoMap::BBTPoint>& points,
 		return;
 	}
 
-	while (pos < upper) {
+	while (pos >= 0 && pos < upper) {
 		pos = frame_at_beat_locked (_metrics, cnt);
 		const TempoSection tempo = tempo_section_at_frame_locked (_metrics, pos);
 		const MeterSection meter = meter_section_at_frame_locked (_metrics, pos);