diff --git a/libs/ardour/tempo.cc b/libs/ardour/tempo.cc
index d6e33b6b44..d96c712c16 100644
--- a/libs/ardour/tempo.cc
+++ b/libs/ardour/tempo.cc
@@ -2430,7 +2430,7 @@ Evoral::MusicalTime
 TempoMap::framewalk_to_beats (framepos_t pos, framecnt_t distance) const
 {
 	Metrics::const_iterator i;
-	const TempoSection* tempo;
+	const TempoSection* tempo = 0;
 	
 	/* Find the starting tempo */
 
@@ -2447,6 +2447,8 @@ TempoMap::framewalk_to_beats (framepos_t pos, framecnt_t distance) const
 		}
 	}
 
+	assert (tempo);
+
 	/* We now have:
 
 	   tempo -> the Tempo for "pos"