diff --git a/libs/ardour/mtc_slave.cc b/libs/ardour/mtc_slave.cc
index 44386b647f..9a724b74d5 100644
--- a/libs/ardour/mtc_slave.cc
+++ b/libs/ardour/mtc_slave.cc
@@ -373,7 +373,9 @@ MTC_Slave::speed_and_position (double& speed, nframes64_t& pos)
 		/* scale elapsed time by the current MTC speed */
 
 		if (last.timestamp && (now > last.timestamp)) {
-			elapsed = (nframes_t) floor (speed * (now - last.timestamp));
+			elapsed = (nframes_t) floor (last.speed * (now - last.timestamp));
+			DEBUG_TRACE (DEBUG_MTC, string_compose ("last timecode received @ %1, now = %2, elapsed frames = %3 w/speed= %4\n",
+								last.timestamp, now, elapsed, speed);
 		} else {
 			elapsed = 0; /* XXX is this right? */
 		}