diff --git a/libs/ardour/ltc_slave.cc b/libs/ardour/ltc_slave.cc
index 4f018bb3c5..4ab350fbd7 100644
--- a/libs/ardour/ltc_slave.cc
+++ b/libs/ardour/ltc_slave.cc
@@ -531,7 +531,7 @@ LTC_TransportMaster::pre_process (ARDOUR::pframes_t nframes, samplepos_t now, bo
 		if (skip >= 8192) skip = 8192;
 		unsigned char sound[8192];
 		memset (sound, 0x80, sizeof(char) * skip);
-		ltc_decoder_write (decoder, sound, nframes, now);
+		ltc_decoder_write (decoder, sound, skip, now);
 	} else if (skip != 0) {
 		/* this should never happen. it may if monotonic_cnt, now overflow on 64bit */
 		DEBUG_TRACE (DEBUG::LTC, string_compose("engine skipped %1 samples\n", skip));